diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index c5151f8cc5a7..04a758dc5063 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -13338,7 +13338,9 @@ let
 
   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 {};