--- a/testing/testsuite-targets.mk
+++ b/testing/testsuite-targets.mk
@@ -126,19 +126,17 @@ PKG_STAGE = $(DIST)/test-package-stage
 package-tests: stage-mochitest stage-reftest stage-xpcshell stage-jstests
 else
 # This staging area has been built for us by universal/flight.mk
 PKG_STAGE = $(DIST)/universal/test-package-stage
 endif
 
 package-tests:
 	$(NSINSTALL) -D $(DIST)/$(PKG_PATH)
-	@rm -f "$(DIST)/$(PKG_PATH)$(TEST_PACKAGE)"
-	cd $(PKG_STAGE) && \
-	  zip -r9D "../$(PKG_PATH)$(TEST_PACKAGE)" *
+	@(cd $(PKG_STAGE) && tar $(TAR_CREATE_FLAGS) - *) | bzip2 -f > "$(DIST)/$(PKG_PATH)$(TEST_PACKAGE)"
 
 make-stage-dir:
 	rm -rf $(PKG_STAGE) && $(NSINSTALL) -D $(PKG_STAGE) && $(NSINSTALL) -D $(PKG_STAGE)/bin && $(NSINSTALL) -D $(PKG_STAGE)/bin/components && $(NSINSTALL) -D $(PKG_STAGE)/certs
 
 stage-mochitest: make-stage-dir
 	$(MAKE) -C $(DEPTH)/testing/mochitest stage-package
 
 stage-reftest: make-stage-dir

--- a/toolkit/mozapps/installer/package-name.mk
+++ b/toolkit/mozapps/installer/package-name.mk
@@ -163,17 +163,17 @@ PKG_SRCPACK_BASENAME = $(MOZ_PKG_APPNAME
 PKG_SRCPACK_PATH = source/
 
 endif # MOZ_PKG_PRETTYNAMES
 
 # Symbol package naming
 SYMBOL_ARCHIVE_BASENAME = $(PKG_BASENAME).crashreporter-symbols
 
 # Test package naming
-TEST_PACKAGE = $(PKG_BASENAME).tests.zip
+TEST_PACKAGE = $(PKG_BASENAME).tests.tar.bz2
 
 ifneq (,$(wildcard $(DIST)/bin/application.ini))
 BUILDID = $(shell $(PYTHON) $(MOZILLA_DIR)/config/printconfigsetting.py $(DIST)/bin/application.ini App BuildID)
 else
 BUILDID = $(shell $(PYTHON) $(MOZILLA_DIR)/config/printconfigsetting.py $(DIST)/bin/platform.ini Build BuildID)
 endif
 
 MOZ_SOURCE_STAMP = $(firstword $(shell hg -R $(topsrcdir) parent --template="{node|short}\n" 2>/dev/null))