diff --git a/usr.bin/zstd/Makefile b/usr.bin/zstd/Makefile
--- a/usr.bin/zstd/Makefile
+++ b/usr.bin/zstd/Makefile
@@ -26,6 +26,7 @@
 	zstd.1 zstdcat.1 \
 	zstd.1 zstdmt.1
 
+CSTD=c11
 WARNS?=	2
 LIBADD=	zstd
 .PATH: ${SRCTOP}/sys/contrib/zstd/programs