diff --git a/pkgs/development/python-modules/shiboken2/default.nix b/pkgs/development/python-modules/shiboken2/default.nix
index 998e04cc03fc..9adee3dd4187 100644
--- a/pkgs/development/python-modules/shiboken2/default.nix
+++ b/pkgs/development/python-modules/shiboken2/default.nix
@@ -29,7 +29,7 @@ stdenv.mkDerivation {
     head CMakeLists.txt
   '';
 
-  CLANG_INSTALL_DIR = llvmPackages.libclang.out;
+  env.CLANG_INSTALL_DIR = llvmPackages.libclang.out;
 
   nativeBuildInputs = [
     cmake