diff --git a/sys/conf/kern.mk b/sys/conf/kern.mk
--- a/sys/conf/kern.mk
+++ b/sys/conf/kern.mk
@@ -28,6 +28,9 @@
 .if ${COMPILER_VERSION} >= 100000
 NO_WMISLEADING_INDENTATION=	-Wno-misleading-indentation
 .endif
+.if ${COMPILER_VERSION} >= 130000
+NO_WUNUSED_BUT_SET_VARIABLE=	-Wno-unused-but-set-variable
+.endif
 .if ${COMPILER_VERSION} >= 140000
 NO_WBITWISE_INSTEAD_OF_LOGICAL=	-Wno-bitwise-instead-of-logical
 .endif
@@ -90,10 +93,6 @@
 FORMAT_EXTENSIONS=	-Wno-format
 .elif ${COMPILER_TYPE} == "clang"
 FORMAT_EXTENSIONS=	-D__printf__=__freebsd_kprintf__
-# Only newer versions of clang have -Wno-unused-but-set-variable
-.if ${COMPILER_VERSION} >= 130000
-NO_WUNUSED_BUT_SET_VARIABLE=-Wno-unused-but-set-variable
-.endif
 .else
 FORMAT_EXTENSIONS=	-fformat-extensions
 .endif