diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 6a9523e..530b067 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -700,7 +700,7 @@
 
 #if defined(MBEDTLS_HAVE_TIME)
     t = mbedtls_time( NULL );
-    p = mbedtls_platform_put_uint32_be( p, t );
+    p = mbedtls_platform_put_uint32_be( p, (uint32_t) t );
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, current time: %lu", t ) );
 #else
     if( ( ret = mbedtls_ssl_conf_get_frng( ssl->conf )