diff --git a/pkgs/by-name/wi/wiimms-iso-tools/package.nix b/pkgs/by-name/wi/wiimms-iso-tools/package.nix
index 5c6d35117502..703cbbf37f56 100644
--- a/pkgs/by-name/wi/wiimms-iso-tools/package.nix
+++ b/pkgs/by-name/wi/wiimms-iso-tools/package.nix
@@ -42,7 +42,7 @@ stdenv.mkDerivation (finalAttrs: {
     substituteInPlace Makefile --replace gcc "$CC"
   '';
 
-  INSTALL_PATH = "$out";
+  env.INSTALL_PATH = "$out";
 
   installPhase = ''
     mkdir "$out"