diff --git a/cipher-ctr.c b/cipher-ctr.c
index 8561773..8a98f3c 100644
--- a/cipher-ctr.c
+++ b/cipher-ctr.c
@@ -21,11 +21,10 @@
 #include "log.h"
 #include "xmalloc.h"
 
-#if OPENSSL_VERSION_NUMBER < 0x00906000L
-#define SSH_OLD_EVP
-#endif
+/* compatibility with old or broken OpenSSL versions */
+#include "openbsd-compat/openssl-compat.h"
 
-#if OPENSSL_VERSION_NUMBER < 0x00907000L
+#ifdef USE_BUILTIN_RIJNDAEL
 #include "rijndael.h"
 #define AES_KEY rijndael_ctx
 #define AES_BLOCK_SIZE 16