diff --git a/toolkit/mozapps/installer/packager.mk b/toolkit/mozapps/installer/packager.mk
index bdc150655de..a55e4beb167 100644
--- a/toolkit/mozapps/installer/packager.mk
+++ b/toolkit/mozapps/installer/packager.mk
@@ -482,10 +482,11 @@ PRECOMPILE_RESOURCE=gre
 PRECOMPILE_GRE=$$PWD
 endif
 
+# Silence the unzip step so we don't print any binary data from the comment field.
 GENERATE_CACHE = \
   $(_ABS_RUN_TEST_PROGRAM) $(LIBXUL_DIST)/bin/xpcshell$(BIN_SUFFIX) -g "$(PRECOMPILE_GRE)" -a "$$PWD" -f $(call core_abspath,$(MOZILLA_DIR)/toolkit/mozapps/installer/precompile_cache.js) -e "populate_startupcache('$(PRECOMPILE_DIR)', '$(OMNIJAR_NAME)', 'startupCache.zip');" && \
   rm -rf jsloader && \
-  $(UNZIP) startupCache.zip && \
+  $(UNZIP) -q startupCache.zip && \
   rm startupCache.zip && \
   $(ZIP) -r9m $(OMNIJAR_NAME) jsloader/resource/$(PRECOMPILE_RESOURCE)
 else