--- a/build/moz-automation.mk
+++ b/build/moz-automation.mk
@@ -1,13 +1,18 @@
 #
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+ifndef ENABLE_TESTS
+# We can't package tests if they aren't enabled.
+MOZ_AUTOMATION_PACKAGE_TESTS = 0
+endif
+
 ifneq (,$(filter automation/%,$(MAKECMDGOALS)))
 ifeq (4.0,$(firstword $(sort 4.0 $(MAKE_VERSION))))
 MAKEFLAGS += --output-sync=target
 else
 .NOTPARALLEL:
 endif
 endif