diff --git a/sys/conf/kern.mk b/sys/conf/kern.mk
--- a/sys/conf/kern.mk
+++ b/sys/conf/kern.mk
@@ -367,7 +367,7 @@
 .PHONY: ${PHONY_NOTMAIN}
 .NOTMAIN: ${PHONY_NOTMAIN}
 
-CSTD?=		gnu99
+CSTD?=		gnu17
 
 # c99/gnu99 is the minimum C standard version supported for kernel build
 .if ${CSTD} == "k&r" || ${CSTD} == "c89" || ${CSTD} == "c90" || \