diff --git a/os/io.c b/os/io.c
index e7b76b9ce..167b40a72 100644
--- a/os/io.c
+++ b/os/io.c
@@ -394,6 +394,8 @@ ReadRequestFromClient(ClientPtr client)
                     needed = get_big_req_len(request, client);
             }
             client->req_len = needed;
+            if (needed > MAXINT >> 2)
+                return -(BadLength);
             needed <<= 2;
         }
         if (gotnow < needed) {