diff --git a/pkgs/development/libraries/qt-5/hooks/wrap-qt-apps-hook.sh b/pkgs/development/libraries/qt-5/hooks/wrap-qt-apps-hook.sh
index 94df0a1a8e66..413368268aa2 100644
--- a/pkgs/development/libraries/qt-5/hooks/wrap-qt-apps-hook.sh
+++ b/pkgs/development/libraries/qt-5/hooks/wrap-qt-apps-hook.sh
@@ -65,7 +65,7 @@ qtOwnPathsHook() {
     qtHostPathHook "${!outputBin}"
 }
 
-preFixupPhases+=" qtOwnPathsHook"
+appendToVar preFixupPhases qtOwnPathsHook
 
 # Note: $qtWrapperArgs still gets defined even if ${dontWrapQtApps-} is set.
 wrapQtAppsHook() {