diff --git a/default.nix b/default.nix
index 11c71ad..6e487c9 100644
--- a/default.nix
+++ b/default.nix
@@ -16,7 +16,7 @@ buildDunePackage {
   src = ./.;
   duneVersion = "3";
   postPatch = ''
-    substituteInPlace --replace "flake_env" "$out/bin/flake_env" direnvrc
+    substituteInPlace direnvrc --replace "flake_env" "$out/bin/flake_env"
   '';
   postInstall = ''
     install -m400 -D direnvrc $out/share/flake_env/direnvrc