--- a/toolkit/components/thumbnails/test/Makefile.in
+++ b/toolkit/components/thumbnails/test/Makefile.in
@@ -17,15 +17,20 @@ MOCHITEST_BROWSER_FILES := \
 	background_red_scroll.html \
 	background_red_redirect.sjs \
 	privacy_cache_control.sjs \
 	$(NULL)
 
 ifndef RELEASE_BUILD
 MOCHITEST_BROWSER_FILES += \
 	browser_thumbnails_background.js \
-	browser_thumbnails_background_crash.js \
 	browser_thumbnails_update.js \
 	thumbnails_background.sjs \
-	thumbnails_crash_content_helper.js \
 	thumbnails_update.sjs \
 	$(NULL)
+
+ifdef MOZ_CRASHREPORTER
+MOCHITEST_BROWSER_FILES += \
+	browser_thumbnails_background_crash.js \
+	thumbnails_crash_content_helper.js \
+	$(NULL)
 endif
+endif