diff --git a/xpcom/Makefile.in b/xpcom/Makefile.in
index 3850df43e4a..9881392d430 100644
--- a/xpcom/Makefile.in
+++ b/xpcom/Makefile.in
@@ -21,8 +21,6 @@ srcdir		= @srcdir@
 
 include $(DEPTH)/config/autoconf.mk
 
-DIRS	= public src
-
-#DIRS += tests
+DIRS	= public src tests
 
 include $(topsrcdir)/config/rules.mk