diff --git a/share/mk/bsd.sys.mk b/share/mk/bsd.sys.mk
index 7a231a356cc..961aa7dce15 100644
--- a/share/mk/bsd.sys.mk
+++ b/share/mk/bsd.sys.mk
@@ -119,6 +119,7 @@ CWARNFLAGS+=	-Wno-unknown-pragmas
 CLANG_NO_IAS=	 -no-integrated-as
 CLANG_OPT_SMALL= -mstack-alignment=8 -mllvm -inline-threshold=3\
 		 -mllvm -enable-load-pre=false -mllvm -simplifycfg-dup-ret
+CFLAGS+=	 -Qunused-arguments
 CFLAGS+=	 ${CFLAGS.clang}
 CXXFLAGS+=	 ${CXXFLAGS.clang}
 .else # !CLANG