diff --git a/pkgs/build-support/rust/fetch-cargo-vendor.nix b/pkgs/build-support/rust/fetch-cargo-vendor.nix
index e346ab659af6..7c7c8b793342 100644
--- a/pkgs/build-support/rust/fetch-cargo-vendor.nix
+++ b/pkgs/build-support/rust/fetch-cargo-vendor.nix
@@ -56,6 +56,8 @@ let
     {
       name = "${name}-vendor-staging";
 
+      impureEnvVars = lib.fetchers.proxyImpureEnvVars;
+
       nativeBuildInputs =
         [
           fetchCargoVendorUtil