diff --git a/haskell/cabal.bzl b/haskell/cabal.bzl
index 081ab0c021..2b65a72e58 100644
--- a/haskell/cabal.bzl
+++ b/haskell/cabal.bzl
@@ -164,8 +164,9 @@ def _cabal_toolchain_info(hs, cc, workspace_name, runghc):
     # TODO: remove this if Bazel fixes its behavior.
     # Upstream ticket: https://github.com/bazelbuild/bazel/issues/5127.
     ar = cc.tools.ar
-    if ar.find("libtool") >= 0:
-        ar = "/usr/bin/ar"
+    if paths.basename(ar) == "libtool":
+        # assume `ar` is available at the same place as `libtool`
+        ar = paths.join(paths.dirname(ar), "ar")
 
     return struct(
         ghc = hs.tools.ghc.path,
diff --git a/haskell/cc.bzl b/haskell/cc.bzl
index 201b9a18cc..93e50c692f 100644
--- a/haskell/cc.bzl
+++ b/haskell/cc.bzl
@@ -136,8 +136,10 @@ def cc_interop_info(ctx, override_cc_toolchain = None):
     # "/usr/bin/libtool". Since we call ar directly, override it.
     # TODO: remove this if Bazel fixes its behavior.
     # Upstream ticket: https://github.com/bazelbuild/bazel/issues/5127.
-    if tools["ar"].find("libtool") >= 0:
-        tools["ar"] = "/usr/bin/ar"
+    ar_tool = tools["ar"]
+    if paths.basename(ar_tool) == "libtool":
+        # assume `ar` is available at the same place as `libtool`
+        tools["ar"] = paths.join(paths.dirname(ar_tool), "ar")
 
     env = {}
     if hs_toolchain.is_darwin: