diff --git a/pkgs/development/interpreters/python/hooks/python-output-dist-hook.sh b/pkgs/development/interpreters/python/hooks/python-output-dist-hook.sh
index 83b79d01fa40..8e4a15dc277f 100644
--- a/pkgs/development/interpreters/python/hooks/python-output-dist-hook.sh
+++ b/pkgs/development/interpreters/python/hooks/python-output-dist-hook.sh
@@ -21,4 +21,4 @@ EOF
     echo "Finished executing pythonOutputDistPhase"
 }
 
-preFixupPhases+=" pythonOutputDistPhase"
+appendToVar preFixupPhases pythonOutputDistPhase