diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index ef94b94cea4..5a05669559b 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -13704,7 +13704,9 @@ in
 
   pcsx2 = callPackage_i686 ../misc/emulators/pcsx2 { };
 
-  pencil = callPackage ../applications/graphics/pencil { };
+  pencil = callPackage ../applications/graphics/pencil {
+    xulrunner = firefox-unwrapped;
+  };
 
   perseus = callPackage ../applications/science/math/perseus {};