diff --git a/embedding/components/commandhandler/src/Makefile.in b/embedding/components/commandhandler/src/Makefile.in
index f4963cd27e9d..d41163aa4679 100644
--- a/embedding/components/commandhandler/src/Makefile.in
+++ b/embedding/components/commandhandler/src/Makefile.in
@@ -12,6 +12,7 @@ include $(DEPTH)/config/autoconf.mk
 
 LIBRARY_NAME	= commandhandler_s
 LIBXUL_LIBRARY	= 1
+FAIL_ON_WARNINGS = 1
 
 CPPSRCS		= \
       nsBaseCommandController.cpp \