diff --git a/usr.sbin/ppp/Makefile b/usr.sbin/ppp/Makefile
index a7a35d49295..3e70da14eaf 100644
--- a/usr.sbin/ppp/Makefile
+++ b/usr.sbin/ppp/Makefile
@@ -66,6 +66,7 @@ SRCS+=	id.c
 CFLAGS+=-DNODES
 .else
 SRCS+=	chap_ms.c mppe.c
+CFLAGS+=	-DOPENSSL_API_COMPAT=0x10100000L
 LIBADD+=	crypto
 .endif