--- a/toolkit/mozapps/installer/upload-files.mk
+++ b/toolkit/mozapps/installer/upload-files.mk
@@ -234,17 +234,17 @@ endif
 
 # For final GPG / authenticode signing / dmg signing if required
 ifdef MOZ_EXTERNAL_SIGNING_FORMAT
   MOZ_SIGN_PACKAGE_CMD=$(MOZ_SIGN_CMD) $(foreach f,$(MOZ_EXTERNAL_SIGNING_FORMAT),-f $(f))
 endif
 
 ifdef MOZ_SIGN_PREPARED_PACKAGE_CMD
   ifeq (Darwin, $(OS_ARCH))
-    MAKE_PACKAGE    = cd ./$(PKG_DMG_SOURCE) && $(MOZ_SIGN_PREPARED_PACKAGE_CMD) $(MOZ_MACBUNDLE_NAME) \
+    MAKE_PACKAGE    = cd ./$(PKG_DMG_SOURCE) && $(MOZ_SIGN_PREPARED_PACKAGE_CMD) '$(MOZ_MACBUNDLE_NAME)' \
                       && cd $(PACKAGE_BASE_DIR) && $(INNER_MAKE_PACKAGE)
   else
     MAKE_PACKAGE    = $(MOZ_SIGN_PREPARED_PACKAGE_CMD) $(MOZ_PKG_DIR) \
                       && $(INNER_MAKE_PACKAGE)
   endif #Darwin
 
 else
   MAKE_PACKAGE    = $(INNER_MAKE_PACKAGE)