diff --git a/pkgs/build-support/rust/fetch-cargo-vendor.nix b/pkgs/build-support/rust/fetch-cargo-vendor.nix
index 2802bf9e73f1..f97c270e731a 100644
--- a/pkgs/build-support/rust/fetch-cargo-vendor.nix
+++ b/pkgs/build-support/rust/fetch-cargo-vendor.nix
@@ -3,7 +3,7 @@
   stdenvNoCC,
   runCommand,
   writers,
-  python3Packages,
+  python3,
   cargo,
   gitMinimal,
   nix-prefetch-git,
@@ -11,6 +11,14 @@
 }:
 
 let
+  python = python3.override {
+    self = python;
+    packageOverrides = final: prev: {
+      charset-normalier = prev.charset-normalizer.override { withMypyc = false; };
+    };
+  };
+  python3Packages = python.pkgs;
+
   replaceWorkspaceValues = writers.writePython3Bin "replace-workspace-values" {
     libraries = with python3Packages; [
       tomli
diff --git a/pkgs/development/python-modules/charset-normalizer/default.nix b/pkgs/development/python-modules/charset-normalizer/default.nix
index 5137ceb0e83f..c3650a402f17 100644
--- a/pkgs/development/python-modules/charset-normalizer/default.nix
+++ b/pkgs/development/python-modules/charset-normalizer/default.nix
@@ -8,6 +8,7 @@
   pytestCheckHook,
   requests,
   setuptools,
+  withMypyc ? !isPyPy,
 }:
 
 buildPythonPackage rec {
@@ -30,9 +31,9 @@ buildPythonPackage rec {
   build-system = [
     setuptools
   ]
-  ++ lib.optional (!isPyPy) mypy;
+  ++ lib.optional (withMypyc) mypy;
 
-  env.CHARSET_NORMALIZER_USE_MYPYC = lib.optionalString (!isPyPy) "1";
+  env.CHARSET_NORMALIZER_USE_MYPYC = lib.optionalString (withMypyc) "1";
 
   nativeCheckInputs = [ pytestCheckHook ];