diff --git a/secure/lib/libcrypto/Makefile b/secure/lib/libcrypto/Makefile
index fe50e93d3b5..60d551f5c4f 100644
--- a/secure/lib/libcrypto/Makefile
+++ b/secure/lib/libcrypto/Makefile
@@ -248,6 +248,8 @@ SRCS+=	buildinf.h
 INCS+=	opensslconf.h evp.h
 INCSDIR=	${INCLUDEDIR}/openssl
 
+CSTD=	c89
+
 CLEANFILES=	buildinf.h opensslconf.h evp.h
 
 buildinf.h: