diff --git "a/dll/win32/winhttp/request.c" "b/dll/win32/winhttp/request.c"
index da28f7b1826..23e77fe7b7a 100644
--- "a/dll/win32/winhttp/request.c"
+++ "b/dll/win32/winhttp/request.c"
@@ -2996,6 +2996,9 @@ done:
 static void task_query_data_available( struct task_header *task )
 {
     struct query_data *q = (struct query_data *)task;
+#ifdef __REACTOS__
+    q->available = 0; // Uninitialized variable needs to be zeroed
+#endif
     query_data_available( q->hdr.request, q->available, TRUE );
 }