diff --git a/lib/default.nix b/lib/default.nix
index 7bd02106f7b6b..cbe0a0ba21b59 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -47,7 +47,7 @@ let
     filesystem = callLibs ./filesystem.nix;
 
     # back-compat aliases
-    platforms = systems.doubles;
+    platforms = systems.forMeta;
 
     inherit (builtins) add addErrorContext attrNames
       concatLists deepSeq elem elemAt filter genericClosure genList
diff --git a/lib/meta.nix b/lib/meta.nix
index 07b1710fff70a..199030c103af5 100644
--- a/lib/meta.nix
+++ b/lib/meta.nix
@@ -67,4 +67,23 @@ rec {
   */
   hiPrioSet = set: mapDerivationAttrset hiPrio set;
 
+
+  /* Check to see if a platform is matched by the given `meta.platforms`
+     element.
+
+     A `meta.platform` pattern is either
+
+       1. (legacy) a system string.
+
+       2. (modern) a pattern for the platform `parsed` field.
+
+     We can inject these into a patten for the whole of a structured platform,
+     and then match that.
+  */
+  platformMatch = platform: elem: let
+      pattern =
+        if builtins.isString elem
+        then { system = elem; }
+        else { parsed = elem; };
+    in lib.matchAttrs pattern platform;
 }
diff --git a/lib/systems/default.nix b/lib/systems/default.nix
index d5a206e620c82..bd408e00bb142 100644
--- a/lib/systems/default.nix
+++ b/lib/systems/default.nix
@@ -3,6 +3,7 @@
 
 rec {
   doubles = import ./doubles.nix { inherit lib; };
+  forMeta = import ./for-meta.nix { inherit lib; };
   parse = import ./parse.nix { inherit lib; };
   inspect = import ./inspect.nix { inherit lib; };
   platforms = import ./platforms.nix { inherit lib; };
diff --git a/lib/systems/doubles.nix b/lib/systems/doubles.nix
index 20294a28a1107..012a1786a3ccb 100644
--- a/lib/systems/doubles.nix
+++ b/lib/systems/doubles.nix
@@ -24,19 +24,20 @@ let
 in rec {
   inherit all;
 
-  allBut = platforms: lists.filter (x: !(builtins.elem x platforms)) all;
   none = [];
 
   arm     = filterDoubles predicates.isArm;
+  aarch64 = filterDoubles predicates.isAarch64;
+  x86     = filterDoubles predicates.isx86;
   i686    = filterDoubles predicates.isi686;
-  mips    = filterDoubles predicates.isMips;
   x86_64  = filterDoubles predicates.isx86_64;
+  mips    = filterDoubles predicates.isMips;
 
   cygwin  = filterDoubles predicates.isCygwin;
   darwin  = filterDoubles predicates.isDarwin;
   freebsd = filterDoubles predicates.isFreeBSD;
   # Should be better, but MinGW is unclear, and HURD is bit-rotted.
-  gnu     = filterDoubles (matchAttrs { kernel = parse.kernels.linux;  abi = parse.abis.gnu; });
+  gnu     = filterDoubles (matchAttrs { kernel = parse.kernels.linux; abi = parse.abis.gnu; });
   illumos = filterDoubles predicates.isSunOS;
   linux   = filterDoubles predicates.isLinux;
   netbsd  = filterDoubles predicates.isNetBSD;
diff --git a/lib/systems/for-meta.nix b/lib/systems/for-meta.nix
new file mode 100644
index 0000000000000..63f24b4653553
--- /dev/null
+++ b/lib/systems/for-meta.nix
@@ -0,0 +1,30 @@
+{ lib }:
+let
+  inherit (lib.systems) parse;
+  inherit (lib.systems.inspect) patterns;
+
+in rec {
+  all     = [ {} ]; # `{}` matches anything
+  none    = [];
+
+  arm     = [ patterns.isArm ];
+  aarch64 = [ patterns.isAarch64 ];
+  x86     = [ patterns.isx86 ];
+  i686    = [ patterns.isi686 ];
+  x86_64  = [ patterns.isx86_64 ];
+  mips    = [ patterns.isMips ];
+
+  cygwin  = [ patterns.isCygwin ];
+  darwin  = [ patterns.isDarwin ];
+  freebsd = [ patterns.isFreeBSD ];
+  # Should be better, but MinGW is unclear, and HURD is bit-rotted.
+  gnu     = [ { kernel = parse.kernels.linux; abi = parse.abis.gnu; } ];
+  illumos = [ patterns.isSunOS ];
+  linux   = [ patterns.isLinux ];
+  netbsd  = [ patterns.isNetBSD ];
+  openbsd = [ patterns.isOpenBSD ];
+  unix    = patterns.isUnix; # Actually a list
+  windows = [ patterns.isWindows ];
+
+  inherit (lib.systems.doubles) mesaPlatforms;
+}
diff --git a/lib/systems/inspect.nix b/lib/systems/inspect.nix
index ab220af46e303..a7bd17f68a459 100644
--- a/lib/systems/inspect.nix
+++ b/lib/systems/inspect.nix
@@ -5,51 +5,49 @@ with lib.lists;
 
 rec {
   patterns = rec {
-    i686         = { cpu = cpuTypes.i686; };
-    x86_64       = { cpu = cpuTypes.x86_64; };
-    PowerPC      = { cpu = cpuTypes.powerpc; };
-    x86          = { cpu = { family = "x86"; }; };
-    Arm          = { cpu = { family = "arm"; }; };
-    Aarch64      = { cpu = { family = "aarch64"; }; };
-    Mips         = { cpu = { family = "mips"; }; };
-    RiscV        = { cpu = { family = "riscv"; }; };
-    Wasm         = { cpu = { family = "wasm"; }; };
-
-    "32bit"      = { cpu = { bits = 32; }; };
-    "64bit"      = { cpu = { bits = 64; }; };
-    BigEndian    = { cpu = { significantByte = significantBytes.bigEndian; }; };
-    LittleEndian = { cpu = { significantByte = significantBytes.littleEndian; }; };
-
-    BSD          = { kernel = { families = { inherit (kernelFamilies) bsd; }; }; };
-    Unix         = [ BSD Darwin Linux SunOS Hurd Cygwin ];
-
-    Darwin       = { kernel = kernels.darwin; };
-    Linux        = { kernel = kernels.linux; };
-    SunOS        = { kernel = kernels.solaris; };
-    FreeBSD      = { kernel = kernels.freebsd; };
-    Hurd         = { kernel = kernels.hurd; };
-    NetBSD       = { kernel = kernels.netbsd; };
-    OpenBSD      = { kernel = kernels.openbsd; };
-    Windows      = { kernel = kernels.windows; };
-    Cygwin       = { kernel = kernels.windows; abi = abis.cygnus; };
-    MinGW        = { kernel = kernels.windows; abi = abis.gnu; };
-
-    Android      = [ { abi = abis.android; } { abi = abis.androideabi; } ];
-    Musl         = with abis; map (a: { abi = a; }) [ musl musleabi musleabihf ];
-
-    Kexecable    = map (family: { kernel = kernels.linux; cpu.family = family; })
-                     [ "x86" "arm" "aarch64" "mips" ];
-    Efi          = map (family: { cpu.family = family; })
-                     [ "x86" "arm" "aarch64" ];
-    Seccomputable = map (family: { kernel = kernels.linux; cpu.family = family; })
-                      [ "x86" "arm" "aarch64" "mips" ];
+    isi686         = { cpu = cpuTypes.i686; };
+    isx86_64       = { cpu = cpuTypes.x86_64; };
+    isPowerPC      = { cpu = cpuTypes.powerpc; };
+    isx86          = { cpu = { family = "x86"; }; };
+    isArm          = { cpu = { family = "arm"; }; };
+    isAarch64      = { cpu = { family = "aarch64"; }; };
+    isMips         = { cpu = { family = "mips"; }; };
+    isRiscV        = { cpu = { family = "riscv"; }; };
+    isWasm         = { cpu = { family = "wasm"; }; };
+
+    is32bit        = { cpu = { bits = 32; }; };
+    is64bit        = { cpu = { bits = 64; }; };
+    isBigEndian    = { cpu = { significantByte = significantBytes.bigEndian; }; };
+    isLittleEndian = { cpu = { significantByte = significantBytes.littleEndian; }; };
+
+    isBSD          = { kernel = { families = { inherit (kernelFamilies) bsd; }; }; };
+    isUnix         = [ isBSD isDarwin isLinux isSunOS isHurd isCygwin ];
+
+    isDarwin       = { kernel = kernels.darwin; };
+    isLinux        = { kernel = kernels.linux; };
+    isSunOS        = { kernel = kernels.solaris; };
+    isFreeBSD      = { kernel = kernels.freebsd; };
+    isHurd         = { kernel = kernels.hurd; };
+    isNetBSD       = { kernel = kernels.netbsd; };
+    isOpenBSD      = { kernel = kernels.openbsd; };
+    isWindows      = { kernel = kernels.windows; };
+    isCygwin       = { kernel = kernels.windows; abi = abis.cygnus; };
+    isMinGW        = { kernel = kernels.windows; abi = abis.gnu; };
+
+    isAndroid      = [ { abi = abis.android; } { abi = abis.androideabi; } ];
+    isMusl         = with abis; map (a: { abi = a; }) [ musl musleabi musleabihf ];
+
+    isKexecable    = map (family: { kernel = kernels.linux; cpu.family = family; })
+                       [ "x86" "arm" "aarch64" "mips" ];
+    isEfi          = map (family: { cpu.family = family; })
+                       [ "x86" "arm" "aarch64" ];
+    isSeccomputable = map (family: { kernel = kernels.linux; cpu.family = family; })
+                        [ "x86" "arm" "aarch64" "mips" ];
   };
 
   matchAnyAttrs = patterns:
     if builtins.isList patterns then attrs: any (pattern: matchAttrs pattern attrs) patterns
     else matchAttrs patterns;
 
-  predicates = mapAttrs'
-    (name: value: nameValuePair ("is" + name) (matchAnyAttrs value))
-    patterns;
+  predicates = mapAttrs (_: matchAnyAttrs) patterns;
 }
diff --git a/nixos/release.nix b/nixos/release.nix
index 9d41d954a01b9..cd0ce6dc7b185 100644
--- a/nixos/release.nix
+++ b/nixos/release.nix
@@ -16,15 +16,14 @@ let
     inherit system;
   } // args);
 
-  # Note: only supportedSystems are considered.
-  callTestOnTheseSystems = systems: fn: args:
-    forTheseSystems
-      (intersectLists supportedSystems systems)
+  callTestOnMatchingSystems = systems: fn: args:
+    forMatchingSystems
+      systems
       (system: hydraJob (importTest fn args system));
-  callTest = callTestOnTheseSystems supportedSystems;
+  callTest = callTestOnMatchingSystems supportedSystems;
 
-  callSubTests = callSubTestsOnTheseSystems supportedSystems;
-  callSubTestsOnTheseSystems = systems: fn: args: let
+  callSubTests = callSubTestsOnMatchingSystems supportedSystems;
+  callSubTestsOnMatchingSystems = systems: fn: args: let
     discover = attrs: let
       subTests = filterAttrs (const (hasAttr "test")) attrs;
     in mapAttrs (const (t: hydraJob t.test)) subTests;
@@ -138,7 +137,7 @@ in rec {
   # Build the initial ramdisk so Hydra can keep track of its size over time.
   initialRamdisk = buildFromConfig ({ pkgs, ... }: { }) (config: config.system.build.initialRamdisk);
 
-  netboot = forTheseSystems [ "x86_64-linux" "aarch64-linux" ] (system: makeNetboot {
+  netboot = forMatchingSystems [ "x86_64-linux" "aarch64-linux" ] (system: makeNetboot {
     inherit system;
     modules = [
       ./modules/installer/netboot/netboot-minimal.nix
@@ -152,7 +151,7 @@ in rec {
     inherit system;
   });
 
-  iso_graphical = forTheseSystems [ "x86_64-linux" ] (system: makeIso {
+  iso_graphical = forMatchingSystems [ "x86_64-linux" ] (system: makeIso {
     module = ./modules/installer/cd-dvd/installation-cd-graphical-kde.nix;
     type = "graphical";
     inherit system;
@@ -160,7 +159,7 @@ in rec {
 
   # A variant with a more recent (but possibly less stable) kernel
   # that might support more hardware.
-  iso_minimal_new_kernel = forTheseSystems [ "x86_64-linux" ] (system: makeIso {
+  iso_minimal_new_kernel = forMatchingSystems [ "x86_64-linux" ] (system: makeIso {
     module = ./modules/installer/cd-dvd/installation-cd-minimal-new-kernel.nix;
     type = "minimal-new-kernel";
     inherit system;
@@ -172,7 +171,7 @@ in rec {
   });
 
   # A bootable VirtualBox virtual appliance as an OVA file (i.e. packaged OVF).
-  ova = forTheseSystems [ "x86_64-linux" ] (system:
+  ova = forMatchingSystems [ "x86_64-linux" ] (system:
 
     with import nixpkgs { inherit system; };
 
@@ -248,9 +247,9 @@ in rec {
   tests.boot-stage1 = callTest tests/boot-stage1.nix {};
   tests.borgbackup = callTest tests/borgbackup.nix {};
   tests.buildbot = callTest tests/buildbot.nix {};
-  tests.cadvisor = callTestOnTheseSystems ["x86_64-linux"] tests/cadvisor.nix {};
-  tests.ceph = callTestOnTheseSystems ["x86_64-linux"] tests/ceph.nix {};
-  tests.chromium = (callSubTestsOnTheseSystems ["x86_64-linux"] tests/chromium.nix {}).stable or {};
+  tests.cadvisor = callTestOnMatchingSystems ["x86_64-linux"] tests/cadvisor.nix {};
+  tests.ceph = callTestOnMatchingSystems ["x86_64-linux"] tests/ceph.nix {};
+  tests.chromium = (callSubTestsOnMatchingSystems ["x86_64-linux"] tests/chromium.nix {}).stable or {};
   tests.cjdns = callTest tests/cjdns.nix {};
   tests.cloud-init = callTest tests/cloud-init.nix {};
   tests.containers-ipv4 = callTest tests/containers-ipv4.nix {};
@@ -264,21 +263,21 @@ in rec {
   tests.containers-hosts = callTest tests/containers-hosts.nix {};
   tests.containers-macvlans = callTest tests/containers-macvlans.nix {};
   tests.couchdb = callTest tests/couchdb.nix {};
-  tests.docker = callTestOnTheseSystems ["x86_64-linux"] tests/docker.nix {};
-  tests.docker-tools = callTestOnTheseSystems ["x86_64-linux"] tests/docker-tools.nix {};
-  tests.docker-edge = callTestOnTheseSystems ["x86_64-linux"] tests/docker-edge.nix {};
+  tests.docker = callTestOnMatchingSystems ["x86_64-linux"] tests/docker.nix {};
+  tests.docker-tools = callTestOnMatchingSystems ["x86_64-linux"] tests/docker-tools.nix {};
+  tests.docker-edge = callTestOnMatchingSystems ["x86_64-linux"] tests/docker-edge.nix {};
   tests.dovecot = callTest tests/dovecot.nix {};
-  tests.dnscrypt-proxy = callTestOnTheseSystems ["x86_64-linux"] tests/dnscrypt-proxy.nix {};
+  tests.dnscrypt-proxy = callTestOnMatchingSystems ["x86_64-linux"] tests/dnscrypt-proxy.nix {};
   tests.ecryptfs = callTest tests/ecryptfs.nix {};
-  tests.etcd = callTestOnTheseSystems ["x86_64-linux"] tests/etcd.nix {};
-  tests.ec2-nixops = (callSubTestsOnTheseSystems ["x86_64-linux"] tests/ec2.nix {}).boot-ec2-nixops or {};
-  tests.ec2-config = (callSubTestsOnTheseSystems ["x86_64-linux"] tests/ec2.nix {}).boot-ec2-config or {};
-  tests.elk = callSubTestsOnTheseSystems ["x86_64-linux"] tests/elk.nix {};
+  tests.etcd = callTestOnMatchingSystems ["x86_64-linux"] tests/etcd.nix {};
+  tests.ec2-nixops = (callSubTestsOnMatchingSystems ["x86_64-linux"] tests/ec2.nix {}).boot-ec2-nixops or {};
+  tests.ec2-config = (callSubTestsOnMatchingSystems ["x86_64-linux"] tests/ec2.nix {}).boot-ec2-config or {};
+  tests.elk = callSubTestsOnMatchingSystems ["x86_64-linux"] tests/elk.nix {};
   tests.env = callTest tests/env.nix {};
   tests.ferm = callTest tests/ferm.nix {};
   tests.firefox = callTest tests/firefox.nix {};
   tests.firewall = callTest tests/firewall.nix {};
-  tests.fleet = callTestOnTheseSystems ["x86_64-linux"] tests/fleet.nix {};
+  tests.fleet = callTestOnMatchingSystems ["x86_64-linux"] tests/fleet.nix {};
   tests.fwupd = callTest tests/fwupd.nix {};
   #tests.gitlab = callTest tests/gitlab.nix {};
   tests.gitolite = callTest tests/gitolite.nix {};
@@ -311,7 +310,7 @@ in rec {
   tests.kernel-copperhead = callTest tests/kernel-copperhead.nix {};
   tests.kernel-latest = callTest tests/kernel-latest.nix {};
   tests.kernel-lts = callTest tests/kernel-lts.nix {};
-  tests.kubernetes = callSubTestsOnTheseSystems ["x86_64-linux"] tests/kubernetes/default.nix {};
+  tests.kubernetes = callSubTestsOnMatchingSystems ["x86_64-linux"] tests/kubernetes/default.nix {};
   tests.latestKernel.login = callTest tests/login.nix { latestKernel = true; };
   tests.ldap = callTest tests/ldap.nix {};
   #tests.lightdm = callTest tests/lightdm.nix {};
@@ -341,14 +340,14 @@ in rec {
   tests.nginx = callTest tests/nginx.nix { };
   tests.nghttpx = callTest tests/nghttpx.nix { };
   tests.nix-ssh-serve = callTest tests/nix-ssh-serve.nix { };
-  tests.novacomd = callTestOnTheseSystems ["x86_64-linux"] tests/novacomd.nix { };
+  tests.novacomd = callTestOnMatchingSystems ["x86_64-linux"] tests/novacomd.nix { };
   tests.leaps = callTest tests/leaps.nix { };
   tests.nsd = callTest tests/nsd.nix {};
   tests.openssh = callTest tests/openssh.nix {};
   tests.openldap = callTest tests/openldap.nix {};
   tests.owncloud = callTest tests/owncloud.nix {};
   tests.pam-oath-login = callTest tests/pam-oath-login.nix {};
-  #tests.panamax = callTestOnTheseSystems ["x86_64-linux"] tests/panamax.nix {};
+  #tests.panamax = callTestOnMatchingSystems ["x86_64-linux"] tests/panamax.nix {};
   tests.peerflix = callTest tests/peerflix.nix {};
   tests.php-pcre = callTest tests/php-pcre.nix {};
   tests.postgresql = callSubTests tests/postgresql.nix {};
@@ -382,7 +381,7 @@ in rec {
   tests.tomcat = callTest tests/tomcat.nix {};
   tests.udisks2 = callTest tests/udisks2.nix {};
   tests.vault = callTest tests/vault.nix {};
-  tests.virtualbox = callSubTestsOnTheseSystems ["x86_64-linux"] tests/virtualbox.nix {};
+  tests.virtualbox = callSubTestsOnMatchingSystems ["x86_64-linux"] tests/virtualbox.nix {};
   tests.wordpress = callTest tests/wordpress.nix {};
   tests.xfce = callTest tests/xfce.nix {};
   tests.xmonad = callTest tests/xmonad.nix {};
diff --git a/pkgs/applications/graphics/ahoviewer/default.nix b/pkgs/applications/graphics/ahoviewer/default.nix
index 2d42a479999ba..b7647803b3d39 100644
--- a/pkgs/applications/graphics/ahoviewer/default.nix
+++ b/pkgs/applications/graphics/ahoviewer/default.nix
@@ -37,7 +37,9 @@ stdenv.mkDerivation rec {
     description = "A GTK2 image viewer, manga reader, and booru browser";
     maintainers = with maintainers; [ skrzyp xzfc ];
     license = licenses.mit;
-    platforms = platforms.allBut [ "darwin" "cygwin" ];
+    # Unintentionally not working on Darwin:
+    # https://github.com/ahodesuka/ahoviewer/issues/62
+    platforms = platforms.linux;
   };
 }
 
diff --git a/pkgs/applications/misc/robo3t/default.nix b/pkgs/applications/misc/robo3t/default.nix
index fc7ff48423948..8928ee18064db 100644
--- a/pkgs/applications/misc/robo3t/default.nix
+++ b/pkgs/applications/misc/robo3t/default.nix
@@ -58,7 +58,7 @@ stdenv.mkDerivation rec {
     mkdir -p $out/share/icons
     cp ${icon} $out/share/icons/robomongo.png
 
-    patchelf --set-interpreter ${stdenv.glibc}/lib/ld-linux-x86-64.so.2 $BASEDIR/bin/robo3t
+    patchelf --set-interpreter ${stdenv.cc.libc}/lib/ld-linux-x86-64.so.2 $BASEDIR/bin/robo3t
 
     mkdir $out/bin
 
@@ -70,7 +70,7 @@ stdenv.mkDerivation rec {
   meta = {
     homepage = https://robomongo.org/;
     description = "Query GUI for mongodb";
-    platforms = stdenv.lib.intersectLists stdenv.lib.platforms.linux stdenv.lib.platforms.x86_64;
+    platforms = [ "x86_64-linux" ];
     license = stdenv.lib.licenses.gpl3;
     maintainers = [ stdenv.lib.maintainers.eperuffo ];
   };
diff --git a/pkgs/applications/networking/instant-messengers/pond/default.nix b/pkgs/applications/networking/instant-messengers/pond/default.nix
index 002d0345a0007..5d463648bd8bc 100644
--- a/pkgs/applications/networking/instant-messengers/pond/default.nix
+++ b/pkgs/applications/networking/instant-messengers/pond/default.nix
@@ -2,7 +2,6 @@
   fetchgit, fetchhg, fetchbzr, fetchsvn }:
 
 let
-  isx86_64 = stdenv.lib.any (n: n == stdenv.system) stdenv.lib.platforms.x86_64;
   gui = true; # Might be implemented with nixpkgs config.
 in
 buildGoPackage rec {
@@ -22,11 +21,11 @@ buildGoPackage rec {
 
   nativeBuildInputs = [ pkgconfig ];
   buildInputs = [ trousers gtk3 gtkspell3 ]
-    ++ stdenv.lib.optional isx86_64 dclxvi
+    ++ stdenv.lib.optional stdenv.hostPlatform.isx86_64 dclxvi
     ++ stdenv.lib.optionals gui [ wrapGAppsHook ];
   buildFlags = stdenv.lib.optionalString (!gui) "-tags nogui";
   excludedPackages = "\\(appengine\\|bn256cgo\\)";
-  postPatch = stdenv.lib.optionalString isx86_64 ''
+  postPatch = stdenv.lib.optionalString stdenv.hostPlatform.isx86_64 ''
     grep -r 'bn256' | awk -F: '{print $1}' | xargs sed -i \
       -e "s,golang.org/x/crypto/bn256,github.com/agl/pond/bn256cgo,g" \
       -e "s,bn256\.,bn256cgo.,g"
diff --git a/pkgs/applications/window-managers/i3/lock-color.nix b/pkgs/applications/window-managers/i3/lock-color.nix
index ec1673f5040dd..edaa88bde23d8 100644
--- a/pkgs/applications/window-managers/i3/lock-color.nix
+++ b/pkgs/applications/window-managers/i3/lock-color.nix
@@ -34,6 +34,6 @@ stdenv.mkDerivation rec {
 
     # Needs the SSE2 instruction set. See upstream issue
     # https://github.com/chrjguill/i3lock-color/issues/44
-    platforms = platforms.i686 ++ platforms.x86_64;
+    platforms = platforms.x86;
   };
 }
diff --git a/pkgs/data/icons/numix-icon-theme-square/default.nix b/pkgs/data/icons/numix-icon-theme-square/default.nix
index 198229cce3711..99871abe5d464 100644
--- a/pkgs/data/icons/numix-icon-theme-square/default.nix
+++ b/pkgs/data/icons/numix-icon-theme-square/default.nix
@@ -29,7 +29,7 @@ stdenv.mkDerivation rec {
     description = "Numix icon theme (square version)";
     homepage = https://numixproject.org;
     license = licenses.gpl3;
-    platforms = with platforms; allBut darwin;
+    platforms = platforms.linux; # Maybe other non-darwin Unix
     maintainers = with maintainers; [ romildo ];
   };
 }
diff --git a/pkgs/development/compilers/chicken/default.nix b/pkgs/development/compilers/chicken/default.nix
index 4a2893c303f43..ad9e57f794f0d 100644
--- a/pkgs/development/compilers/chicken/default.nix
+++ b/pkgs/development/compilers/chicken/default.nix
@@ -63,7 +63,7 @@ stdenv.mkDerivation {
     homepage = http://www.call-cc.org/;
     license = stdenv.lib.licenses.bsd3;
     maintainers = with stdenv.lib.maintainers; [ the-kenny ];
-    platforms = with stdenv.lib.platforms; allBut darwin;
+    platforms = stdenv.lib.platforms.linux; # Maybe other non-darwin Unix
     description = "A portable compiler for the Scheme programming language";
     longDescription = ''
       CHICKEN is a compiler for the Scheme programming language.
diff --git a/pkgs/development/compilers/mono/generic.nix b/pkgs/development/compilers/mono/generic.nix
index a8012f6bb9e63..3b476bce0273c 100644
--- a/pkgs/development/compilers/mono/generic.nix
+++ b/pkgs/development/compilers/mono/generic.nix
@@ -88,7 +88,7 @@ stdenv.mkDerivation rec {
   meta = {
     homepage = http://mono-project.com/;
     description = "Cross platform, open source .NET development framework";
-    platforms = with stdenv.lib.platforms; allBut [ "aarch64-linux" ];
+    platforms = stdenv.lib.platforms.x86;
     maintainers = with stdenv.lib.maintainers; [ viric thoughtpolice obadz vrthra ];
     license = stdenv.lib.licenses.free; # Combination of LGPL/X11/GPL ?
   };
diff --git a/pkgs/development/haskell-modules/generic-builder.nix b/pkgs/development/haskell-modules/generic-builder.nix
index a29056d965ac1..0e676c4201867 100644
--- a/pkgs/development/haskell-modules/generic-builder.nix
+++ b/pkgs/development/haskell-modules/generic-builder.nix
@@ -34,8 +34,8 @@ in
 , enableStaticLibraries ? true
 , extraLibraries ? [], librarySystemDepends ? [], executableSystemDepends ? []
 , homepage ? "http://hackage.haskell.org/package/${pname}"
-, platforms ? ghc.meta.platforms
-, hydraPlatforms ? platforms
+, platforms ? with stdenv.lib.platforms; unix ++ windows # GHC can cross-compile
+, hydraPlatforms ? null
 , hyperlinkSource ? true
 , isExecutable ? false, isLibrary ? !isExecutable
 , jailbreak ? false
@@ -403,7 +403,7 @@ stdenv.mkDerivation ({
          // optionalAttrs broken               { inherit broken; }
          // optionalAttrs (description != "")  { inherit description; }
          // optionalAttrs (maintainers != [])  { inherit maintainers; }
-         // optionalAttrs (hydraPlatforms != platforms) { inherit hydraPlatforms; }
+         // optionalAttrs (hydraPlatforms != null) { inherit hydraPlatforms; }
          ;
 
 }
diff --git a/pkgs/development/libraries/buddy/default.nix b/pkgs/development/libraries/buddy/default.nix
index 313ac086726ff..00e236eba8c3d 100644
--- a/pkgs/development/libraries/buddy/default.nix
+++ b/pkgs/development/libraries/buddy/default.nix
@@ -18,7 +18,7 @@ stdenv.mkDerivation rec {
     description = "Binary decision diagram package";
     license = "as-is";
 
-    platforms = with stdenv.lib.platforms; allBut cygwin;
+    platforms = stdenv.lib.platforms.unix; # Once had cygwin problems
     maintainers = [ stdenv.lib.maintainers.peti ];
   };
 }
diff --git a/pkgs/development/libraries/cln/default.nix b/pkgs/development/libraries/cln/default.nix
index 9d7c9c4f30f85..e39386dca3f43 100644
--- a/pkgs/development/libraries/cln/default.nix
+++ b/pkgs/development/libraries/cln/default.nix
@@ -15,6 +15,6 @@ stdenv.mkDerivation rec {
     description = "C/C++ library for numbers, a part of GiNaC";
     homepage = http://www.ginac.de/CLN/;
     maintainers = [ ];
-    platforms = with stdenv.lib.platforms; allBut cygwin;
+    platforms = stdenv.lib.platforms.unix; # Once had cygwin problems
   };
 }
diff --git a/pkgs/development/libraries/cloog-ppl/default.nix b/pkgs/development/libraries/cloog-ppl/default.nix
index 2c49e0363589f..442b115a40822 100644
--- a/pkgs/development/libraries/cloog-ppl/default.nix
+++ b/pkgs/development/libraries/cloog-ppl/default.nix
@@ -69,6 +69,6 @@ stdenv.mkDerivation rec {
        make[3]: *** [Box.lo] Error 1
 
     */
-    platforms = with stdenv.lib.platforms; allBut cygwin;
+    platforms = stdenv.lib.platforms.unix; # Once had cygwin problems
   };
 }
diff --git a/pkgs/development/libraries/cloog/0.18.0.nix b/pkgs/development/libraries/cloog/0.18.0.nix
index ccd938283199d..fa4e19f716ae8 100644
--- a/pkgs/development/libraries/cloog/0.18.0.nix
+++ b/pkgs/development/libraries/cloog/0.18.0.nix
@@ -58,6 +58,6 @@ stdenv.mkDerivation rec {
        make[3]: *** [Box.lo] Error 1
 
     */
-    platforms = with stdenv.lib.platforms; allBut cygwin;
+    platforms = stdenv.lib.platforms.unix; # Once had cygwin problems
   };
 }
diff --git a/pkgs/development/libraries/cloog/default.nix b/pkgs/development/libraries/cloog/default.nix
index 5da29273a8be7..902e0b26687b9 100644
--- a/pkgs/development/libraries/cloog/default.nix
+++ b/pkgs/development/libraries/cloog/default.nix
@@ -59,6 +59,6 @@ stdenv.mkDerivation rec {
        make[3]: *** [Box.lo] Error 1
 
     */
-    platforms = with stdenv.lib.platforms; allBut cygwin;
+    platforms = stdenv.lib.platforms.unix; # Once had cygwin problems
   };
 }
diff --git a/pkgs/development/libraries/libatomic_ops/default.nix b/pkgs/development/libraries/libatomic_ops/default.nix
index 714e9361440c5..c22fb8a2cba2d 100644
--- a/pkgs/development/libraries/libatomic_ops/default.nix
+++ b/pkgs/development/libraries/libatomic_ops/default.nix
@@ -26,6 +26,6 @@ stdenv.mkDerivation rec {
     description = ''A library for semi-portable access to hardware-provided atomic memory update operations'';
     license = stdenv.lib.licenses.gpl2Plus ;
     maintainers = [stdenv.lib.maintainers.raskin];
-    platforms = stdenv.lib.platforms.unix;
+    platforms = with stdenv.lib.platforms; unix ++ windows;
   };
 }
diff --git a/pkgs/development/libraries/qt-5/modules/qtbase.nix b/pkgs/development/libraries/qt-5/modules/qtbase.nix
index 3a0a7326f762c..c6473ff188a72 100644
--- a/pkgs/development/libraries/qt-5/modules/qtbase.nix
+++ b/pkgs/development/libraries/qt-5/modules/qtbase.nix
@@ -30,7 +30,6 @@ assert withGtk3 -> dconf != null;
 assert withGtk3 -> gtk3 != null;
 
 let
-  system-x86_64 = lib.elem stdenv.system lib.platforms.x86_64;
   compareVersion = v: builtins.compareVersions version v;
 in
 
@@ -258,7 +257,7 @@ stdenv.mkDerivation {
       "-no-warnings-are-errors"
     ]
     ++ (
-      if (!system-x86_64)
+      if (!stdenv.hostPlatform.isx86_64)
       then [ "-no-sse2" ]
       else lib.optional (compareVersion "5.9.0" >= 0) [ "-sse2" ]
     )
diff --git a/pkgs/development/libraries/rocksdb/default.nix b/pkgs/development/libraries/rocksdb/default.nix
index 562942f230fb4..6ccb78003cfae 100644
--- a/pkgs/development/libraries/rocksdb/default.nix
+++ b/pkgs/development/libraries/rocksdb/default.nix
@@ -73,7 +73,7 @@ stdenv.mkDerivation rec {
     homepage = http://rocksdb.org;
     description = "A library that provides an embeddable, persistent key-value store for fast storage";
     license = licenses.bsd3;
-    platforms = platforms.allBut [ "i686-linux" ];
+    platforms = platforms.x86_64 ++ platforms.aarch64;
     maintainers = with maintainers; [ adev wkennington ];
   };
 }
diff --git a/pkgs/development/libraries/wiredtiger/default.nix b/pkgs/development/libraries/wiredtiger/default.nix
index 9d11b98b1cbd1..c905c40cf9603 100644
--- a/pkgs/development/libraries/wiredtiger/default.nix
+++ b/pkgs/development/libraries/wiredtiger/default.nix
@@ -15,7 +15,7 @@ let
   mkWith = mkFlag "with-" "without-";
   mkOther = mkFlag "" "" true;
 
-  shouldUsePkg = pkg: if pkg != null && any (x: x == stdenv.system) pkg.meta.platforms then pkg else null;
+  shouldUsePkg = pkg: if pkg != null && pkg.meta.available then pkg else null;
 
   optLz4 = shouldUsePkg lz4;
   optSnappy = shouldUsePkg snappy;
diff --git a/pkgs/development/pharo/vm/build-vm-legacy.nix b/pkgs/development/pharo/vm/build-vm-legacy.nix
index 66cef77e5a949..f2fd6eebd56eb 100644
--- a/pkgs/development/pharo/vm/build-vm-legacy.nix
+++ b/pkgs/development/pharo/vm/build-vm-legacy.nix
@@ -70,9 +70,9 @@ stdenv.mkDerivation rec {
     license = stdenv.lib.licenses.mit;
     maintainers = [ stdenv.lib.maintainers.lukego ];
     # Pharo VM sources are packaged separately for darwin (OS X)
-    platforms = with stdenv.lib;
-                  intersectLists
-                    platforms.mesaPlatforms
-                    (subtractLists platforms.darwin platforms.unix);
+    platforms = stdenv.lib.filter
+      (system: with stdenv.lib.systems.elaborate { inherit system; };
+         isUnix && !isDarwin)
+      stdenv.lib.platforms.mesaPlatforms;
   };
 }
diff --git a/pkgs/development/pharo/wrapper/default.nix b/pkgs/development/pharo/wrapper/default.nix
index f60b8a6d20386..084c46cd5b51b 100644
--- a/pkgs/development/pharo/wrapper/default.nix
+++ b/pkgs/development/pharo/wrapper/default.nix
@@ -2,7 +2,7 @@
 
 stdenv.mkDerivation rec {
   name = "pharo";
-  src = ./.;
+  src = ./pharo-vm.sh;
   inherit cog32 spur32 spur64 file;
   magic = ./magic;
   desktopItem = makeDesktopItem {
@@ -17,6 +17,10 @@ stdenv.mkDerivation rec {
     categories = "Development;";
     mimeType = "application/x-pharo-image";
   };
+  unpackPhase = ''
+    cp $src ./pharo-vm.sh
+    sourceRoot=$PWD
+  '';
   buildPhase = ''
     substituteAllInPlace ./pharo-vm.sh
   '';
@@ -49,10 +53,10 @@ stdenv.mkDerivation rec {
     license = stdenv.lib.licenses.mit;
     maintainers = [ stdenv.lib.maintainers.lukego ];
     # Pharo VM sources are packaged separately for darwin (OS X)
-    platforms = with stdenv.lib;
-                  intersectLists
-                    platforms.mesaPlatforms
-                    (subtractLists platforms.darwin platforms.unix);
+    platforms = stdenv.lib.filter
+      (system: with stdenv.lib.systems.elaborate { inherit system; };
+         isUnix && !isDarwin)
+      stdenv.lib.platforms.mesaPlatforms;
   };
 }
 
diff --git a/pkgs/development/tools/rtags/default.nix b/pkgs/development/tools/rtags/default.nix
index 13fbea3fc2312..a2c75a02aa28a 100644
--- a/pkgs/development/tools/rtags/default.nix
+++ b/pkgs/development/tools/rtags/default.nix
@@ -32,6 +32,6 @@ stdenv.mkDerivation rec {
     description = "C/C++ client-server indexer based on clang";
     homepage = https://github.com/andersbakken/rtags;
     license = stdenv.lib.licenses.gpl3;
-    platforms = stdenv.lib.platforms.allBut [ "i686-linux" ];
+    platforms = with stdenv.lib.platforms; x86_64 ++ aarch64;
   };
 }
diff --git a/pkgs/games/endless-sky/default.nix b/pkgs/games/endless-sky/default.nix
index 40dbd1d33a77d..8e1bd52eb42fe 100644
--- a/pkgs/games/endless-sky/default.nix
+++ b/pkgs/games/endless-sky/default.nix
@@ -41,6 +41,6 @@ stdenv.mkDerivation rec {
       gpl3Plus cc-by-sa-30 cc-by-sa-40 publicDomain
     ];
     maintainers = with maintainers; [ lheckemann ];
-    platforms = with platforms; allBut darwin;
+    platforms = platforms.linux; # Maybe other non-darwin Unix
   };
 }
diff --git a/pkgs/games/nethack/default.nix b/pkgs/games/nethack/default.nix
index d9ab3ee833b23..b67a79aa3fe77 100644
--- a/pkgs/games/nethack/default.nix
+++ b/pkgs/games/nethack/default.nix
@@ -2,11 +2,11 @@
 
 let
   platform =
-    if lib.elem stdenv.system lib.platforms.unix then "unix"
+    if stdenv.hostPlatform.isUnix then "unix"
     else throw "Unknown platform for NetHack: ${stdenv.system}";
   unixHint =
-    if stdenv.isLinux then "linux"
-    else if stdenv.isDarwin then "macosx10.10"
+    /**/ if stdenv.hostPlatform.isLinux  then "linux"
+    else if stdenv.hostPlatform.isDarwin then "macosx10.10"
     # We probably want something different for Darwin
     else "unix";
   userDir = "~/.config/nethack";
diff --git a/pkgs/misc/jackaudio/default.nix b/pkgs/misc/jackaudio/default.nix
index a6396fc8c28bf..52b0abc48a7a5 100644
--- a/pkgs/misc/jackaudio/default.nix
+++ b/pkgs/misc/jackaudio/default.nix
@@ -15,7 +15,7 @@
 with stdenv.lib;
 let
   inherit (python2Packages) python dbus-python;
-  shouldUsePkg = pkg: if pkg != null && stdenv.lib.any (x: x == stdenv.system) pkg.meta.platforms then pkg else null;
+  shouldUsePkg = pkg: if pkg != null && pkg.meta.available then pkg else null;
 
   libOnly = prefix == "lib";
 
diff --git a/pkgs/misc/jackaudio/jack1.nix b/pkgs/misc/jackaudio/jack1.nix
index 28ce85bd8a3f0..43d23dd525ae4 100644
--- a/pkgs/misc/jackaudio/jack1.nix
+++ b/pkgs/misc/jackaudio/jack1.nix
@@ -5,7 +5,7 @@
 }:
 
 let
-  shouldUsePkg = pkg: if pkg != null && stdenv.lib.any (x: x == stdenv.system) pkg.meta.platforms then pkg else null;
+  shouldUsePkg = pkg: if pkg != null && pkg.meta.available then pkg else null;
 
   optAlsaLib = shouldUsePkg alsaLib;
   optDb = shouldUsePkg db;
diff --git a/pkgs/misc/screensavers/alock/default.nix b/pkgs/misc/screensavers/alock/default.nix
index 1dc03e1e9f032..5b7c12dee1b03 100644
--- a/pkgs/misc/screensavers/alock/default.nix
+++ b/pkgs/misc/screensavers/alock/default.nix
@@ -38,7 +38,7 @@ stdenv.mkDerivation rec {
       xscreensaver and never will. It's just for locking the current
       X session.
     '';
-    platforms = with platforms; allBut cygwin;
+    platforms = platforms.unix; # Cygwin had problems at one point
     maintainers = with maintainers; [ ftrvxmtrx chris-martin ];
   };
 }
diff --git a/pkgs/misc/screensavers/xscreensaver/default.nix b/pkgs/misc/screensavers/xscreensaver/default.nix
index b337b6cb0e90e..8035e7da37db8 100644
--- a/pkgs/misc/screensavers/xscreensaver/default.nix
+++ b/pkgs/misc/screensavers/xscreensaver/default.nix
@@ -50,7 +50,7 @@ stdenv.mkDerivation rec {
     homepage = https://www.jwz.org/xscreensaver/;
     description = "A set of screensavers";
     maintainers = with stdenv.lib.maintainers; [ raskin ];
-    platforms = with stdenv.lib.platforms; allBut cygwin;
+    platforms = stdenv.lib.platforms.unix; # Once had cygwin problems
     inherit version;
     downloadPage = "https://www.jwz.org/xscreensaver/download.html";
     updateWalker = true;
diff --git a/pkgs/os-specific/linux/ffado/default.nix b/pkgs/os-specific/linux/ffado/default.nix
index 4e2d2b388419d..4e3e373d244c7 100644
--- a/pkgs/os-specific/linux/ffado/default.nix
+++ b/pkgs/os-specific/linux/ffado/default.nix
@@ -11,7 +11,7 @@
 
 let
 
-  shouldUsePkg = pkg: if pkg != null && stdenv.lib.any (x: x == stdenv.system) pkg.meta.platforms then pkg else null;
+  shouldUsePkg = pkg: if pkg != null && pkg.meta.available then pkg else null;
 
   libOnly = prefix == "lib";
 
diff --git a/pkgs/servers/http/nginx/generic.nix b/pkgs/servers/http/nginx/generic.nix
index de30870bee834..ff0a4c65b4a60 100644
--- a/pkgs/servers/http/nginx/generic.nix
+++ b/pkgs/servers/http/nginx/generic.nix
@@ -55,7 +55,7 @@ stdenv.mkDerivation {
     "--with-mail_ssl_module"
   ]
     ++ optional (gd != null) "--with-http_image_filter_module"
-    ++ optional (elem stdenv.system (with platforms; linux ++ freebsd)) "--with-file-aio"
+    ++ optional (with stdenv.hostPlatform; isLinux || isFreeBSD) "--with-file-aio"
     ++ map (mod: "--add-module=${mod.src}") modules;
 
   NIX_CFLAGS_COMPILE = [ "-I${libxml2.dev}/include/libxml2" ] ++ optional stdenv.isDarwin "-Wno-error=deprecated-declarations";
diff --git a/pkgs/servers/shishi/default.nix b/pkgs/servers/shishi/default.nix
index 535571f46e201..1540a6f1fd18d 100644
--- a/pkgs/servers/shishi/default.nix
+++ b/pkgs/servers/shishi/default.nix
@@ -14,7 +14,7 @@ let
   mkWith = mkFlag "with-" "without-";
   mkOther = mkFlag "" "" true;
 
-  shouldUsePkg = pkg: if pkg != null && stdenv.lib.any (x: x == stdenv.system) pkg.meta.platforms then pkg else null;
+  shouldUsePkg = pkg: if pkg != null && pkg.meta.available then pkg else null;
 
   optPam = shouldUsePkg pam;
   optLibidn = shouldUsePkg libidn;
diff --git a/pkgs/stdenv/generic/check-meta.nix b/pkgs/stdenv/generic/check-meta.nix
index a1878dc01367f..113b95f3ab00c 100644
--- a/pkgs/stdenv/generic/check-meta.nix
+++ b/pkgs/stdenv/generic/check-meta.nix
@@ -1,11 +1,9 @@
 # Checks derivation meta and attrs for problems (like brokenness,
 # licenses, etc).
 
-{ lib, config, system, meta, derivationArg, mkDerivationArg }:
+{ lib, config, hostPlatform, meta }:
 
 let
-  attrs = mkDerivationArg; # TODO: probably get rid of passing this one
-
   # See discussion at https://github.com/NixOS/nixpkgs/pull/25304#issuecomment-298385426
   # for why this defaults to false, but I (@copumpkin) want to default it to true soon.
   shouldCheckMeta = config.checkMeta or false;
@@ -123,7 +121,7 @@ let
 
       '';
 
-  handleEvalIssue = { reason , errormsg ? "" }:
+  handleEvalIssue = attrs: { reason , errormsg ? "" }:
     let
       msg = ''
         Package ‘${attrs.name or "«name-missing»"}’ in ${pos_str} ${errormsg}, refusing to evaluate.
@@ -146,7 +144,7 @@ let
     license = either (listOf lib.types.attrs) (either lib.types.attrs str);
     maintainers = listOf (attrsOf str);
     priority = int;
-    platforms = listOf str;
+    platforms = listOf (either str lib.systems.parsed.types.system);
     hydraPlatforms = listOf str;
     broken = bool;
 
@@ -175,6 +173,9 @@ let
     else "key '${k}' is unrecognized; expected one of: \n\t      [${lib.concatMapStringsSep ", " (x: "'${x}'") (lib.attrNames metaTypes)}]";
   checkMeta = meta: if shouldCheckMeta then lib.remove null (lib.mapAttrsToList checkMetaAttr meta) else [];
 
+  checkPlatform = attrs:
+    lib.any (lib.meta.platformMatch hostPlatform) attrs.meta.platforms;
+
   # Check if a derivation is valid, that is whether it passes checks for
   # e.g brokenness or license.
   #
@@ -188,19 +189,21 @@ let
       { valid = false; reason = "blacklisted"; errormsg = "has a blacklisted license (‘${showLicense attrs.meta.license}’)"; }
     else if !allowBroken && attrs.meta.broken or false then
       { valid = false; reason = "broken"; errormsg = "is marked as broken"; }
-    else if !allowUnsupportedSystem && !allowBroken && attrs.meta.platforms or null != null && !lib.lists.elem system attrs.meta.platforms then
-      { valid = false; reason = "broken"; errormsg = "is not supported on ‘${system}’"; }
+    else if !allowUnsupportedSystem && !allowBroken && attrs.meta.platforms or null != null && !(checkPlatform attrs) then
+      { valid = false; reason = "broken"; errormsg = "is not supported on ‘${hostPlatform.config}’"; }
     else if !(hasAllowedInsecure attrs) then
       { valid = false; reason = "insecure"; errormsg = "is marked as insecure"; }
     else let res = checkMeta (attrs.meta or {}); in if res != [] then
       { valid = false; reason = "unknown-meta"; errormsg = "has an invalid meta attrset:${lib.concatMapStrings (x: "\n\t - " + x) res}"; }
     else { valid = true; };
 
-   validity = checkValidity attrs;
+  assertValidity = attrs: let
+      validity = checkValidity attrs;
+    in validity // {
+      # Throw an error if trying to evaluate an non-valid derivation
+      handled = if !validity.valid
+        then handleEvalIssue attrs (removeAttrs validity ["valid"])
+        else true;
+  };
 
-in validity // {
-  # Throw an error if trying to evaluate an non-valid derivation
-  handled = if !validity.valid
-    then handleEvalIssue (removeAttrs validity ["valid"])
-    else true;
-}
+in assertValidity
diff --git a/pkgs/stdenv/generic/make-derivation.nix b/pkgs/stdenv/generic/make-derivation.nix
index e8f78d7401f1e..46df958b83967 100644
--- a/pkgs/stdenv/generic/make-derivation.nix
+++ b/pkgs/stdenv/generic/make-derivation.nix
@@ -204,12 +204,11 @@ rec {
         });
 
       validity = import ./check-meta.nix {
-        inherit lib config meta derivationArg;
-        mkDerivationArg = attrs;
+        inherit lib config meta;
         # Nix itself uses the `system` field of a derivation to decide where
         # to build it. This is a bit confusing for cross compilation.
-        inherit (stdenv) system;
-      };
+        inherit (stdenv) hostPlatform;
+      } attrs;
 
       # The meta attribute is passed in the resulting attribute set,
       # but it's not part of the actual derivation, i.e., it's not
diff --git a/pkgs/tools/cd-dvd/dvdisaster/default.nix b/pkgs/tools/cd-dvd/dvdisaster/default.nix
index e70d259df6835..590c32188141e 100644
--- a/pkgs/tools/cd-dvd/dvdisaster/default.nix
+++ b/pkgs/tools/cd-dvd/dvdisaster/default.nix
@@ -33,8 +33,7 @@ stdenv.mkDerivation rec {
     "--docdir=share/doc"
     "--with-nls=yes"
     "--with-embedded-src-path=no"
-  ] ++ stdenv.lib.optional (builtins.elem stdenv.system
-      stdenv.lib.platforms.x86_64) "--with-sse2=yes";
+  ] ++ stdenv.lib.optional (stdenv.hostPlatform.isx86_64) "--with-sse2=yes";
 
   # fatal error: inlined-icons.h: No such file or directory
   enableParallelBuilding = false;
diff --git a/pkgs/tools/filesystems/ceph/generic.nix b/pkgs/tools/filesystems/ceph/generic.nix
index 764f082aa899f..66d74ff5cf736 100644
--- a/pkgs/tools/filesystems/ceph/generic.nix
+++ b/pkgs/tools/filesystems/ceph/generic.nix
@@ -37,8 +37,7 @@ with stdenv.lib;
 let
 
   shouldUsePkg = pkg_: let pkg = (builtins.tryEval pkg_).value;
-    in if lib.any (x: x == system) (pkg.meta.platforms or [])
-      then pkg else null;
+    in if pkg.meta.available or false then pkg else null;
 
   optYasm = shouldUsePkg yasm;
   optFcgi = shouldUsePkg fcgi;
diff --git a/pkgs/tools/graphics/barcode/default.nix b/pkgs/tools/graphics/barcode/default.nix
index d6a31bd5c7f7d..7ed2cc8b6aaf5 100644
--- a/pkgs/tools/graphics/barcode/default.nix
+++ b/pkgs/tools/graphics/barcode/default.nix
@@ -14,7 +14,7 @@ stdenv.mkDerivation rec {
   meta = with stdenv.lib; {
     description = "GNU barcode generator";
     maintainers = with maintainers; [ raskin ];
-    platforms = with platforms; allBut darwin;
+    platforms = platforms.linux; # Maybe other non-darwin Unix
     downloadPage = "http://ftp.gnu.org/gnu/barcode/";
     updateWalker = true;
     homepage = http://ftp.gnu.org/gnu/barcode/;
diff --git a/pkgs/tools/graphics/dcraw/default.nix b/pkgs/tools/graphics/dcraw/default.nix
index 66d3a1100804b..30546865bcc11 100644
--- a/pkgs/tools/graphics/dcraw/default.nix
+++ b/pkgs/tools/graphics/dcraw/default.nix
@@ -23,7 +23,7 @@ stdenv.mkDerivation rec {
     homepage = http://www.cybercom.net/~dcoffin/dcraw/;
     description = "Decoder for many camera raw picture formats";
     license = stdenv.lib.licenses.free;
-    platforms = with stdenv.lib.platforms; allBut cygwin;
+    platforms = stdenv.lib.platforms.unix; # Once had cygwin problems
     maintainers = [ ];
   };
 }
diff --git a/pkgs/tools/misc/mbuffer/default.nix b/pkgs/tools/misc/mbuffer/default.nix
index e81fa7958b5c9..ed6c08d555458 100644
--- a/pkgs/tools/misc/mbuffer/default.nix
+++ b/pkgs/tools/misc/mbuffer/default.nix
@@ -18,6 +18,6 @@ stdenv.mkDerivation rec {
     description  = "A tool for buffering data streams with a large set of unique features";
     license = stdenv.lib.licenses.gpl3;
     maintainers = with stdenv.lib.maintainers; [ tokudan ];
-    platforms = with stdenv.lib.platforms; allBut darwin;
+    platforms = stdenv.lib.platforms.linux; # Maybe other non-darwin Unix
   };
 }
diff --git a/pkgs/tools/networking/dnscrypt-proxy/default.nix b/pkgs/tools/networking/dnscrypt-proxy/default.nix
index 95bfdca6315a3..6120b821bf412 100644
--- a/pkgs/tools/networking/dnscrypt-proxy/default.nix
+++ b/pkgs/tools/networking/dnscrypt-proxy/default.nix
@@ -32,6 +32,6 @@ stdenv.mkDerivation rec {
     license = licenses.isc;
     maintainers = with maintainers; [ joachifm jgeerds ];
     # upstream claims OSX support, but Hydra fails
-    platforms = with platforms; allBut darwin;
+    platforms = platforms.linux; # Maybe other non-darwin Unix
   };
 }
diff --git a/pkgs/tools/networking/zerotierone/default.nix b/pkgs/tools/networking/zerotierone/default.nix
index 37812029c96ca..77df8cbf6f7dc 100644
--- a/pkgs/tools/networking/zerotierone/default.nix
+++ b/pkgs/tools/networking/zerotierone/default.nix
@@ -39,6 +39,6 @@ stdenv.mkDerivation rec {
     homepage = https://www.zerotier.com;
     license = licenses.gpl3;
     maintainers = with maintainers; [ sjmackenzie zimbatm ehmry ];
-    platforms = platforms.allBut [ "i686-linux" ];
+    platforms = platforms.x86_64 ++ platforms.aarch64;
   };
 }
diff --git a/pkgs/top-level/default.nix b/pkgs/top-level/default.nix
index 9cf9eb4db658a..da7fc1bed34c5 100644
--- a/pkgs/top-level/default.nix
+++ b/pkgs/top-level/default.nix
@@ -22,9 +22,9 @@
   # `*Platform`s.
   localSystem
 
-  # The system packages will ultimately be run on. Null if the two should be the
+, # The system packages will ultimately be run on. Null if the two should be the
   # same.
-, crossSystem ? null
+  crossSystem ? null
 
 , # Allow a configuration attribute set to be passed in as an argument.
   config ? {}
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index df5698a31d2a8..ca44b4598ee9e 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -12987,7 +12987,7 @@ in {
       homepage = https://pypi.python.org/pypi/PyICU/;
       description = "Python extension wrapping the ICU C++ API";
       license = licenses.mit;
-      platforms = with platforms; allBut darwin;
+      platforms = platforms.linux; # Maybe other non-darwin Unix
       maintainers = [ maintainers.rycee ];
     };
   };
diff --git a/pkgs/top-level/release-cross.nix b/pkgs/top-level/release-cross.nix
index ef99dbd619e4a..0d15d817a66c1 100644
--- a/pkgs/top-level/release-cross.nix
+++ b/pkgs/top-level/release-cross.nix
@@ -88,7 +88,7 @@ in
         f (["buildPackages"] ++ path) { inherit system crossSystem; }
       );
 
-    testEqual = path: systems: forTheseSystems systems (testEqualOne path);
+    testEqual = path: systems: forMatchingSystems systems (testEqualOne path);
 
     mapTestEqual = lib.mapAttrsRecursive testEqual;
 
diff --git a/pkgs/top-level/release-lib.nix b/pkgs/top-level/release-lib.nix
index 87fb00a9682d4..623c9d9cb000e 100644
--- a/pkgs/top-level/release-lib.nix
+++ b/pkgs/top-level/release-lib.nix
@@ -48,33 +48,56 @@ rec {
   pkgs_x86_64_cygwin = allPackages { system = "x86_64-cygwin"; };
 
 
+  # Given a list of 'meta.platforms'-style patterns, return the sublist of
+  # `supportedSystems` containing systems that matches at least one of the given
+  # patterns.
+  #
+  # This is written in a funny way so that we only elaborate the systems once.
+  supportedMatches = let
+      supportedPlatforms = map
+        (system: lib.systems.elaborate { inherit system; })
+        supportedSystems;
+    in metaPatterns: let
+      anyMatch = platform:
+        lib.any (lib.meta.platformMatch platform) metaPatterns;
+      matchingPlatforms = lib.filter anyMatch supportedPlatforms;
+    in map ({ system, ...}: system) matchingPlatforms;
+
+
   assertTrue = bool:
     if bool
     then pkgs.runCommand "evaluated-to-true" {} "touch $out"
     else pkgs.runCommand "evaluated-to-false" {} "false";
 
+
   /* The working or failing mails for cross builds will be sent only to
      the following maintainers, as most package maintainers will not be
      interested in the result of cross building a package. */
   crossMaintainers = [ maintainers.viric ];
 
+
+  # Generate attributes for all supported systems.
   forAllSystems = genAttrs supportedSystems;
-  forTheseSystems = systems: f:
-    genAttrs (filter (x: elem x supportedSystems) systems) f;
+
+
+  # Generate attributes for all sytems matching at least one of the given
+  # patterns
+  forMatchingSystems = metaPatterns: genAttrs (supportedMatches metaPatterns);
+
 
   /* Build a package on the given set of platforms.  The function `f'
      is called for each supported platform with Nixpkgs for that
      platform as an argument .  We return an attribute set containing
      a derivation for each supported platform, i.e. ‘{ x86_64-linux =
      f pkgs_x86_64_linux; i686-linux = f pkgs_i686_linux; ... }’. */
-  testOn = systems: f: forTheseSystems systems
+  testOn = metaPatterns: f: forMatchingSystems metaPatterns
     (system: hydraJob' (f (pkgsFor system)));
 
 
   /* Similar to the testOn function, but with an additional
      'crossSystem' parameter for allPackages, defining the target
      platform for cross builds. */
-  testOnCross = crossSystem: systems: f: forTheseSystems systems
+  testOnCross = crossSystem: metaPatterns: f: forMatchingSystems metaPatterns
     (system: hydraJob' (f (allPackages { inherit system crossSystem; })));
 
 
@@ -82,14 +105,14 @@ rec {
      map each leaf node to `testOn [platforms...] (pkgs:
      pkgs.<attrPath>)'. */
   mapTestOn = mapAttrsRecursive
-    (path: systems: testOn systems (pkgs: getAttrFromPath path pkgs));
+    (path: metaPatterns: testOn metaPatterns (pkgs: getAttrFromPath path pkgs));
 
 
   /* Similar to the testOn function, but with an additional 'crossSystem'
    * parameter for allPackages, defining the target platform for cross builds,
    * and triggering the build of the host derivation (cross built - crossDrv). */
   mapTestOnCross = crossSystem: mapAttrsRecursive
-    (path: systems: testOnCross crossSystem systems
+    (path: metaPatterns: testOnCross crossSystem metaPatterns
       (pkgs: addMetaAttrs { maintainers = crossMaintainers; } (getAttrFromPath path pkgs)));
 
 
@@ -98,7 +121,8 @@ rec {
   packagePlatforms = mapAttrs (name: value:
     let res = builtins.tryEval (
       if isDerivation value then
-        value.meta.hydraPlatforms or (value.meta.platforms or [ "x86_64-linux" ])
+        value.meta.hydraPlatforms
+          or (supportedMatches (value.meta.platforms or [ "x86_64-linux" ]))
       else if value.recurseForDerivations or false || value.recurseForRelease or false then
         packagePlatforms value
       else
@@ -108,7 +132,7 @@ rec {
 
 
   /* Common platform groups on which to test packages. */
-  inherit (platforms) unix linux darwin cygwin allBut all mesaPlatforms;
+  inherit (platforms) unix linux darwin cygwin all mesaPlatforms;
 
   /* Platform groups for specific kinds of applications. */
   x11Supported = linux;
diff --git a/pkgs/top-level/release-small.nix b/pkgs/top-level/release-small.nix
index 391d79e47f18f..e92ad47e1425e 100644
--- a/pkgs/top-level/release-small.nix
+++ b/pkgs/top-level/release-small.nix
@@ -21,7 +21,7 @@ with import ./release-lib.nix { inherit supportedSystems; };
   atlas = linux;
   autoconf = all;
   automake = all;
-  avahi = allBut cygwin;  # Cygwin builds fail
+  avahi = unix; # Cygwin builds fail
   bash = all;
   bashInteractive = all;
   bc = all;
@@ -54,7 +54,7 @@ with import ./release-lib.nix { inherit supportedSystems; };
   gnumake = all;
   gnupatch = all;
   gnupg = linux;
-  gnuplot = allBut cygwin;
+  gnuplot = unix; # Cygwin builds fail
   gnused = all;
   gnutar = all;
   gnutls = linux;
@@ -128,7 +128,7 @@ with import ./release-lib.nix { inherit supportedSystems; };
   pkgconfig = all;
   pmccabe = linux;
   procps = linux;
-  python = allBut cygwin;
+  python = unix; # Cygwin builds fail
   readline = all;
   rlwrap = all;
   rpm = linux;
@@ -138,9 +138,9 @@ with import ./release-lib.nix { inherit supportedSystems; };
   scrot = linux;
   sdparm = linux;
   sharutils = all;
-  sloccount = allBut cygwin;
+  sloccount = unix; # Cygwin builds fail
   smartmontools = all;
-  sqlite = allBut cygwin;
+  sqlite = unix; # Cygwin builds fail
   squid = linux;
   ssmtp = linux;
   stdenv = all;