diff --git a/src/http.c b/src/http.c
index a240d84a..d0622eba 100644
--- a/src/http.c
+++ b/src/http.c
@@ -994,7 +994,7 @@ void tf_http_request_websocket_send(tf_http_request_t* request, int op_code, con
 	}
 	else
 	{
-		uint32_t high = (size >> 32) & 0xffffffff;
+		uint32_t high = ((uint64_t)size >> 32) & 0xffffffff;
 		uint32_t low = (size >> 0) & 0xffffffff;
 		copy[1] = 127;
 		copy[2] = (high >> 24) & 0xff;