diff --git a/checks/impure/flake-module.nix b/checks/impure/flake-module.nix
index a918c6c2..7683980b 100644
--- a/checks/impure/flake-module.nix
+++ b/checks/impure/flake-module.nix
@@ -7,6 +7,8 @@
         #!${pkgs.bash}/bin/bash
         set -euo pipefail
 
+        unset CLAN_DIR
+
         export PATH="${
           lib.makeBinPath [
             pkgs.gitMinimal