diff --git a/pkgs/development/libraries/kde-frameworks/default.nix b/pkgs/development/libraries/kde-frameworks/default.nix
index aa9f95eebd32..845c911789d0 100644
--- a/pkgs/development/libraries/kde-frameworks/default.nix
+++ b/pkgs/development/libraries/kde-frameworks/default.nix
@@ -42,7 +42,7 @@ let
       propagate = out:
         let setupHook = { writeScript }:
               writeScript "setup-hook" ''
-                if [ "${hookName:-}" != postHook ]; then
+                if [ "''${hookName:-}" != postHook ]; then
                     postHooks+=("source @dev@/nix-support/setup-hook")
                 else
                     # Propagate $dev so that this setup hook is propagated