diff --git a/lib/client-parser.c b/lib/client-parser.c
index 707000b2..3b79f3e2 100644
--- a/lib/client-parser.c
+++ b/lib/client-parser.c
@@ -230,12 +230,27 @@ int libwebsocket_client_rx_sm(struct libwebsocket *wsi, unsigned char c)
 					    (wsi->u.ws.frame_mask_index++) & 3];
 
 		if (--wsi->u.ws.rx_packet_length == 0) {
+			/* spill because we have the whole frame */
 			wsi->lws_rx_parse_state = LWS_RXPS_NEW;
 			goto spill;
 		}
-		if (wsi->u.ws.rx_user_buffer_head !=
-						wsi->protocol->rx_buffer_size)
+
+		/*
+		 * if there's no protocol max frame size given, we are
+		 * supposed to default to LWS_MAX_SOCKET_IO_BUF
+		 */
+
+		if (!wsi->protocol->rx_buffer_size &&
+			 		wsi->u.ws.rx_user_buffer_head !=
+			 				  LWS_MAX_SOCKET_IO_BUF)
 			break;
+		else
+			if (wsi->protocol->rx_buffer_size &&
+					wsi->u.ws.rx_user_buffer_head !=
+						  wsi->protocol->rx_buffer_size)
+			break;
+
+		/* spill because we filled our rx buffer */
 spill:
 
 		handled = 0;