diff --git a/pkgs/applications/editors/emacs/elisp-packages/melpa-packages.nix b/pkgs/applications/editors/emacs/elisp-packages/melpa-packages.nix
index 246786989209..982ff9759066 100644
--- a/pkgs/applications/editors/emacs/elisp-packages/melpa-packages.nix
+++ b/pkgs/applications/editors/emacs/elisp-packages/melpa-packages.nix
@@ -897,7 +897,7 @@ let
                     rm --verbose --force test-bpr.el
                   ''
                 else
-                  previousAttrs;
+                  previousAttrs.preBuild or "";
             }
           );