diff --git a/cf/crypto.m4 b/cf/crypto.m4
index f06703309..5d965cbfc 100644
--- a/cf/crypto.m4
+++ b/cf/crypto.m4
@@ -46,7 +46,7 @@ m4_define([test_body], [
 		MD5_Init(&md5);
 		SHA1_Init(&sha1);
 		SHA256_Init(&sha256);
-		EVP_CIPHER_iv_length(0);
+		EVP_CIPHER_iv_length(((EVP_CIPHER*)0));
 		#ifdef HAVE_OPENSSL
 		RAND_status();
 		UI_UTIL_read_pw_string(0,0,0,0);