diff --git a/sys/conf/kern.mk b/sys/conf/kern.mk
--- a/sys/conf/kern.mk
+++ b/sys/conf/kern.mk
@@ -42,9 +42,6 @@
 		-Wno-error=pointer-sign
 CWARNEXTRA+=	-Wno-error=shift-negative-value
 CWARNEXTRA+=	-Wno-address-of-packed-member
-.if ${COMPILER_VERSION} >= 130000
-CWARNFLAGS+=	-Wno-error=unused-but-set-variable
-.endif
 .endif	# clang
 
 .if ${COMPILER_TYPE} == "gcc"