diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index a7900e40d0..08aaf801f5 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -395,7 +395,7 @@ static int ssl_parse_server_key_exchange( ssl_context *ssl )
         return( POLARSSL_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
     }
 
-    if( ssl->dhm_ctx.len < 64 || ssl->dhm_ctx.len > 256 )
+    if( ssl->dhm_ctx.len < 64 || ssl->dhm_ctx.len > 512 )
     {
         SSL_DEBUG_MSG( 1, ( "bad server key exchange message" ) );
         return( POLARSSL_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );