diff --git a/vms/libssh2_config.h b/vms/libssh2_config.h
index 2eb09a87..b8f73e27 100644
--- a/vms/libssh2_config.h
+++ b/vms/libssh2_config.h
@@ -14,6 +14,7 @@ typedef unsigned int socklen_t; /* missing in headers on VMS */
 /* Have's */
 
 #define HAVE_UNISTD_H
+#define HAVE_STDLIB_H
 #define HAVE_INTTYPES_H
 #define HAVE_SYS_TIME_H
 #define HAVE_SELECT
@@ -23,6 +24,8 @@ typedef unsigned int socklen_t; /* missing in headers on VMS */
 #define HAVE_NETINET_IN_H
 #define HAVE_ARPA_INET_H
 
+#define HAVE_GETTIMEOFDAY 1
+
 #define POSIX_C_SOURCE
 
 /* Enable the possibility of using tracing */
@@ -68,8 +71,11 @@ typedef unsigned int socklen_t; /* missing in headers on VMS */
 
 #endif
 
+/* Use OpenSSL */
+#define LIBSSH2_OPENSSL 1
+
 /* Compile in zlib support. We link against gnv$libzshr, as available
- * on encompasserve.com.
+ * from https://sourceforge.net/projects/vms-ports/files/.
  */
 
 #define LIBSSH2_HAVE_ZLIB