diff --git a/flake.lock b/flake.lock
index 224dd65b..25bf87df 100644
--- a/flake.lock
+++ b/flake.lock
@@ -37,7 +37,32 @@
     "root": {
       "inputs": {
         "flake-utils": "flake-utils",
-        "nixpkgs": "nixpkgs"
+        "nixpkgs": "nixpkgs",
+        "rpypkgs": "rpypkgs"
+      }
+    },
+    "rpypkgs": {
+      "inputs": {
+        "flake-utils": [
+          "flake-utils"
+        ],
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "typhon": "typhon"
+      },
+      "locked": {
+        "lastModified": 1713090744,
+        "narHash": "sha256-ny32FfhDyvQAx0+hKy1DU7RWLjbx6n3zoBRYHT1w2SE=",
+        "ref": "refs/heads/master",
+        "rev": "9a96d9823eef61883f720fc3c600f66e36e4f715",
+        "revCount": 21,
+        "type": "git",
+        "url": "git://git.pf.osdn.net/gitroot/c/co/corbin/rpypkgs.git"
+      },
+      "original": {
+        "type": "git",
+        "url": "git://git.pf.osdn.net/gitroot/c/co/corbin/rpypkgs.git"
       }
     },
     "systems": {
@@ -54,6 +79,31 @@
         "repo": "default",
         "type": "github"
       }
+    },
+    "typhon": {
+      "inputs": {
+        "flake-utils": [
+          "rpypkgs",
+          "flake-utils"
+        ],
+        "nixpkgs": [
+          "rpypkgs",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1707184108,
+        "narHash": "sha256-641r2pA5/mAGX0Dx6/zEP4UtnbS0S0bfOIrJW37ygvA=",
+        "owner": "monte-language",
+        "repo": "typhon",
+        "rev": "fac865f75da5cba9802d2fe7442bec611bd54af4",
+        "type": "github"
+      },
+      "original": {
+        "owner": "monte-language",
+        "repo": "typhon",
+        "type": "github"
+      }
     }
   },
   "root": "root",
diff --git a/flake.nix b/flake.nix
index ebf14b58..1219341a 100644
--- a/flake.nix
+++ b/flake.nix
@@ -4,9 +4,16 @@
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-22.05";
     flake-utils.url = "github:numtide/flake-utils";
+    rpypkgs = {
+      url = "git://git.pf.osdn.net/gitroot/c/co/corbin/rpypkgs.git";
+      inputs = {
+        nixpkgs.follows = "nixpkgs";
+        flake-utils.follows = "flake-utils";
+      };
+    };
   };
 
-  outputs = { self, nixpkgs, flake-utils }:
+  outputs = { self, nixpkgs, flake-utils, rpypkgs }:
     let
       noPythonCheck = p: p.overridePythonAttrs (old: {
         doCheck = false;
@@ -34,7 +41,7 @@
           };
           overlays = [ overlay ];
         };
-        typhon = import ./nix-support/typhon.nix pkgs;
+        typhon = import ./nix-support/typhon.nix { inherit pkgs rpypkgs; };
         qbe = pkgs.stdenv.mkDerivation {
           name = "qbe-unstable";
 
@@ -49,7 +56,7 @@
       in {
         overlays.default = overlay;
         packages = typhon // {
-          default = typhon.fullMonte;
+          default = typhon.monte;
         };
         devShells.default = pkgs.mkShell {
           packages = with pkgs; [ cachix nix-tree ];
diff --git a/nix-support/bench.nix b/nix-support/bench.nix
index 5f79138d..e5652c8c 100644
--- a/nix-support/bench.nix
+++ b/nix-support/bench.nix
@@ -4,7 +4,7 @@ stdenv.mkDerivation {
     name = "typhon-bench";
     buildInputs = [ typhonVm mast ];
     buildPhase = ''
-      ln -s ${typhonVm}/mt-typhon .
+      ln -s ${typhonVm}/bin/mt-typhon .
       ./mt-typhon -l ${mast} -l ${mast}/mast -b ${mast}/loader bench \
          ${mast}/mast/bench/{brot,nqueens,primeCount,richards}
       '';#*/
diff --git a/nix-support/mast.nix b/nix-support/mast.nix
index 8056b528..ef678586 100644
--- a/nix-support/mast.nix
+++ b/nix-support/mast.nix
@@ -10,7 +10,7 @@ let
       then "-noverify"
       else "";
     in pkgs.runCommand name {} ''
-        ${typhonVm}/mt-typhon -l ${boot} ${boot}/loader run montec ${flags} ${mt} $out
+        ${typhonVm}/bin/mt-typhon -l ${boot} ${boot}/loader run montec ${flags} ${mt} $out
       '';
   exts = [ ".mt" ".mt.md" ".asdl" ];
   # Compile a whole tree.
@@ -33,6 +33,6 @@ let
 in buildMASTFarm.overrideAttrs (attrs: {
   # Run the tests in the built tree using the built tree's loader.
   buildCommand = attrs.buildCommand + ''
-    ${typhonVm}/mt-typhon -l $out $out/loader test all-tests
+    ${typhonVm}/bin/mt-typhon -l $out $out/loader test all-tests
   '';
 })
diff --git a/nix-support/monte-script.nix b/nix-support/monte-script.nix
index 732e9745..e2d44d63 100644
--- a/nix-support/monte-script.nix
+++ b/nix-support/monte-script.nix
@@ -87,22 +87,22 @@ let
     case $OPERATION in
         ${buildCmds}
         repl)
-            $RLWRAP ${typhonVm}/mt-typhon -l ${mast} \
+            $RLWRAP ${typhonVm}/bin/mt-typhon -l ${mast} \
               ${mast}/loader run tools/repl
             if [ $? == 1 ]; then
                 echo "Due to a Docker bug, readline-style editing is not currently available in this REPL. Sorry."
-                ${typhonVm}/mt-typhon -l ${mast} \
+                ${typhonVm}/bin/mt-typhon -l ${mast} \
                   ${mast}/loader run tools/repl
             fi
             ;;
         muffin)
             shift
-            ${typhonVm}/mt-typhon -l ${mast} \
+            ${typhonVm}/bin/mt-typhon -l ${mast} \
               ${mast}/loader run tools/muffin "$@"
             ;;
         lint)
             shift
-            ${typhonVm}/mt-typhon -l ${mast} ${mast}/loader \
+            ${typhonVm}/bin/mt-typhon -l ${mast} ${mast}/loader \
                        run montec -lint -terse "$@"
             ;;
         run|test|bench|dot)
@@ -118,7 +118,7 @@ let
                 usage 1
             else
                 DEST=''${3:-''${SOURCE%.mt.mast}}
-                ${typhonVm}/mt-typhon -l ${mast} ${mast}/loader \
+                ${typhonVm}/bin/mt-typhon -l ${mast} ${mast}/loader \
                            run montec -mix "$SOURCE" "$DEST"
             fi
             ;;
@@ -129,12 +129,12 @@ let
             else
                 if [[ "$SOURCE" != *.mast ]]; then
                    MASTSOURCE=''${SOURCE%.mt}.mast
-                   ${typhonVm}/mt-typhon -l ${mast} \
+                   ${typhonVm}/bin/mt-typhon -l ${mast} \
                        ${mast}/loader run montec -mix "$SOURCE" "$MASTSOURCE"
                 SOURCE=$MASTSOURCE
                 fi
                 if [[ "$SOURCE" == *.mast ]]; then
-                    ${typhonVm}/mt-typhon -l ${mast} -l $PWD \
+                    ${typhonVm}/bin/mt-typhon -l ${mast} -l $PWD \
                         ${mast}/loader run ''${SOURCE%.mast} "$@"
                 fi
             fi
@@ -144,7 +144,7 @@ let
             if [[ -z $SOURCE ]]; then
                 usage 1
             else
-                ${typhonVm}/mt-typhon -l ${mast} \
+                ${typhonVm}/bin/mt-typhon -l ${mast} \
                   ${mast}/loader run tools/dump "$SOURCE"
             fi
             ;;
@@ -153,7 +153,7 @@ let
             if [[ -z $SOURCE ]]; then
                 usage 1
             else
-                ${typhonVm}/mt-typhon -l ${mast} \
+                ${typhonVm}/bin/mt-typhon -l ${mast} \
                     ${mast}/loader run format "$SOURCE"
             fi
             ;;
@@ -171,7 +171,7 @@ let
     '';
     capnpc-script = pkgs.writeScript "capnpc-monte" ''
       #!${shellForMt}
-      ${typhonVm}/mt-typhon -l ${mast} \
+      exec ${typhonVm}/bin/mt-typhon -l ${mast} \
           ${mast}/loader run tools/capnpc "$@"
     '';
 
diff --git a/nix-support/montePackage.nix b/nix-support/montePackage.nix
index e663d95f..ac98b5f7 100644
--- a/nix-support/montePackage.nix
+++ b/nix-support/montePackage.nix
@@ -24,7 +24,7 @@ let
       for srcP in ${lib.concatStringsSep " " pathNames}; do
         for srcF in `find ./$srcP -name \\*.mt`; do
           destF=\${srcF%%.mt}.mast
-          ${typhonVm}/mt-typhon -l ${mast}/mast ${mast}/loader run montec -mix $srcF $destF
+          ${typhonVm}/bin/mt-typhon -l ${mast}/mast ${mast}/loader run montec -mix $srcF $destF
           fail=$?
           if [ $fail -ne 0 ]; then
               exit $fail
@@ -34,7 +34,7 @@ let
       ";
       doCheck = doCheck;
       checkPhase = if doCheck then ''
-        ${typhonVm}/mt-typhon ${dependencySearchPaths} -l ${mast}/mast -l . ${mast}/loader test ${entrypoint}
+        ${typhonVm}/bin/mt-typhon ${dependencySearchPaths} -l ${mast}/mast -l . ${mast}/loader test ${entrypoint}
       '' else null;
       installPhase = "
       mkdir -p $out
@@ -70,7 +70,7 @@ let
         for p in ${lib.concatStringsSep " " pathNames}; do
           LOCALPKGPATHS+=" -l $out/$p"
         done
-        ${typhonVm}/mt-typhon ${dependencySearchPaths} \$LOCALPKGPATHS -l ${mast}/mast ${mast}/loader \$OPERATION ${entrypoint} "\$@"
+        ${typhonVm}/bin/mt-typhon ${dependencySearchPaths} \$LOCALPKGPATHS -l ${mast}/mast ${mast}/loader \$OPERATION ${entrypoint} "\$@"
         EOF
         chmod +x $out/bin/${entryPointName}
         '' else "");
diff --git a/nix-support/typhon.nix b/nix-support/typhon.nix
index 517cd848..3b5c382a 100644
--- a/nix-support/typhon.nix
+++ b/nix-support/typhon.nix
@@ -1,6 +1,6 @@
-nixpkgs:
+{ pkgs, rpypkgs }:
 let
-  lib = nixpkgs.lib;
+  lib = pkgs.lib;
   vmSrc = let loc = part: (toString ./..) + part;
    in builtins.filterSource (path: type:
     let p = toString path;
@@ -8,19 +8,17 @@ let
          (type == "directory" || lib.hasSuffix ".py" p)) ||
       p == loc "/typhon" ||
       p == loc "/main.py") ./..;
-  vmConfig = {
-    inherit vmSrc;
-    inherit (nixpkgs) pypy libsodium;
-    pypyPackages = nixpkgs.pypy.pkgs;
-    # Want to build Typhon with Clang instead of GCC? Uncomment this next
-    # line. ~ C.
-    # stdenv = nixpkgs.clangStdenv;
-  };
-  typhon = with nixpkgs; rec {
-    typhonVm = callPackage ./vm.nix (vmConfig // { buildJIT = false; });
-    typhonVmJIT = callPackage ./vm.nix (vmConfig // { buildJIT = true; });
+  typhon = with pkgs; rec {
+    # Want to build Typhon with Clang instead of GCC?
+    # Add `stdenv = pkgs.clangStdenv` to either VM. ~ C.
+    typhonVm = callPackage ./vm.nix {
+      inherit vmSrc rpypkgs; buildJIT = false;
+    };
+    typhonVmJIT = callPackage ./vm.nix {
+      inherit vmSrc rpypkgs; buildJIT = true;
+    };
     mast = callPackage ./mast.nix { typhonVm = typhonVmJIT;
-                                    pkgs = nixpkgs; };
+                                    pkgs = pkgs; };
 
     typhonDumpMAST = callPackage ./dump.nix {};
     # XXX broken for unknown reasons
@@ -28,26 +26,24 @@ let
     monte = callPackage ./monte-script.nix {
       typhonVm = typhonVmJIT; mast = mast;
     };
-    capnMast = callPackage ./capn.nix {
-      pkgs = nixpkgs; monte = monte;
-    };
-    fullMast = nixpkgs.symlinkJoin {
+    capnMast = callPackage ./capn.nix { inherit pkgs monte; };
+    fullMast = pkgs.symlinkJoin {
       name = "mast-full";
       paths = [ mast capnMast ];
     };
     fullMonte = callPackage ./monte-script.nix {
       typhonVm = typhonVmJIT; mast = fullMast;
     };
-    mtBusybox = monte.override { shellForMt = "${nixpkgs.busybox}/bin/sh"; };
+    mtBusybox = monte.override { shellForMt = "${pkgs.busybox}/bin/sh"; };
     mtLite = mtBusybox.override { withBuild = false; };
   };
   typhonDocker = {
-    mtDocker = nixpkgs.dockerTools.buildImage {
+    mtDocker = pkgs.dockerTools.buildImage {
         name = "monte-dev";
         tag = "latest";
-        contents = [nixpkgs.nix.out nixpkgs.busybox typhon.mtBusybox typhon.typhonVmJIT];
+        contents = [pkgs.nix.out pkgs.busybox typhon.mtBusybox typhon.typhonVmJIT];
         runAsRoot = ''
-          #!${nixpkgs.busybox}/bin/sh
+          #!${pkgs.busybox}/bin/sh
           mkdir -p /etc
           tee /etc/profile <<'EOF'
           echo "Try \`monte repl' for an interactive Monte prompt."
@@ -55,11 +51,11 @@ let
           EOF
         '';
         config = {
-            Cmd = [ "${nixpkgs.busybox}/bin/sh" "-l" ];
+            Cmd = [ "${pkgs.busybox}/bin/sh" "-l" ];
             WorkingDir = "/";
             };
         };
-    mtLiteDocker = nixpkgs.dockerTools.buildImage {
+    mtLiteDocker = pkgs.dockerTools.buildImage {
         name = "repl";
         tag = "latest";
         contents = with typhon; [mtLite typhonVmJIT];
diff --git a/nix-support/vm.nix b/nix-support/vm.nix
index 6ec73971..a0da971a 100644
--- a/nix-support/vm.nix
+++ b/nix-support/vm.nix
@@ -1,5 +1,5 @@
-{stdenv, fetchFromGitLab, fetchFromGitHub, lib, libsodium, libuv, libffi,
-pkg-config, pypy, pypyPackages, vmSrc, buildJIT}:
+{ stdenv, fetchFromGitLab, fetchFromGitHub, libsodium, libuv, libffi,
+pypy, system, vmSrc, rpypkgs, buildJIT }:
 
 let
   # https://foss.heptapod.net/pypy/pypy/
@@ -11,29 +11,18 @@ let
     rev = "90fd9ed34d52181de59cbfff863719472b05418e";
     sha256 = "03cshgvh8qcsyac4q4vf0sbvcm1m2ikgwycwip4cc7sw9pzpw6a3";
   };
-  macropy = pypyPackages.buildPythonPackage rec {
-    pname = "macropy";
-    version = "1.0.4";
-    name = "${pname}-${version}";
-    src = fetchFromGitHub {
-      owner = "lihaoyi";
-      repo = "macropy";
-      rev = "13993ccb08df21a0d63b091dbaae50b9dbb3fe3e";
-      sha256 = "12496896c823h0849vnslbdgmn6z9mhfkckqa8sb8k9qqab7pyyl";
-    };
-  };
-  optLevel = if buildJIT then "-Ojit" else "-O2";
-
-in
-stdenv.mkDerivation {
+in rpypkgs.lib.${system}.mkRPythonDerivation {
+  entrypoint = "main.py";
+  binName = "mt-typhon";
+  nativeBuildInputs = with rpypkgs.packages.${system}.rpythonPackages; [ macropy ];
+  buildInputs = [ libuv libsodium ];
+  optLevel = if buildJIT then "jit" else "2";
+} {
   name = if buildJIT then "typhon-vm" else "typhon-vm-nojit";
 
   src = vmSrc;
 
-  buildInputs = [ pypy
-                  pypyPackages.py pypyPackages.pytest
-                  macropy pypySrc
-                  pkg-config libffi libuv libsodium ];
+  # XXX really?
   propagatedBuildInputs = [ libffi libuv libsodium ];
 
   shellHook = ''
@@ -52,20 +41,5 @@ stdenv.mkDerivation {
     trap typhon_cleanup EXIT
   '';
 
-  buildPhase = ''
-    source $stdenv/setup
-    mkdir -p ./rpython/_cache
-    cp -r ${pypySrc}/rpython .
-    chmod -R u+w rpython/
-    cp -r $src/main.py .
-    # Do the actual translation.
-    ${pypy}/bin/pypy -mrpython ${optLevel} main.py
-    '';
-
-  installPhase = ''
-    mkdir $out
-    cp mt-typhon $out/
-    '';
-
   separateDebugInfo = true;
 }
diff --git a/typhon/objects/data.py b/typhon/objects/data.py
index 77a9031c..030a648e 100644
--- a/typhon/objects/data.py
+++ b/typhon/objects/data.py
@@ -25,7 +25,7 @@
 from rpython.rlib.rfloat import DBL_EPSILON, erfc, lgamma
 from rpython.rlib.rstring import StringBuilder, UnicodeBuilder, replace, split
 from rpython.rlib.rstruct.ieee import float_pack
-from rpython.rlib.unicodedata import unicodedb_6_2_0 as unicodedb
+from rpython.rlib.unicodedata import unicodedb_13_0_0 as unicodedb
 
 from typhon.atoms import getAtom
 from typhon.autohelp import autohelp, method
@@ -1453,7 +1453,7 @@ def approxDivideInt(self, other):
             return NAN
         except OverflowError:
             # Trade overflow for reduced dynamic range.
-            negate = self.bi.sign < 0 ^ other < 0
+            negate = self.bi.get_sign() < 0 ^ other < 0
             return NEG_INF if negate else INF
 
     @method("BigInt", "Double", _verb="floorDivide")
diff --git a/typhon/quoting.py b/typhon/quoting.py
index 1d8d1e94..d58caeca 100644
--- a/typhon/quoting.py
+++ b/typhon/quoting.py
@@ -14,7 +14,7 @@
 
 from rpython.rlib.jit import elidable
 from rpython.rlib.rstring import UnicodeBuilder
-from rpython.rlib.unicodedata import unicodedb_6_2_0 as unicodedb
+from rpython.rlib.unicodedata import unicodedb_13_0_0 as unicodedb
 
 
 escapes = {