diff --git a/lib/gui_rpc_client.cpp b/lib/gui_rpc_client.cpp
index f470db65de..b5af3c62df 100644
--- a/lib/gui_rpc_client.cpp
+++ b/lib/gui_rpc_client.cpp
@@ -333,6 +333,7 @@ int RPC_CLIENT::get_reply(char*& mbuf) {
     MFILE mf;
     int n;
 
+    mf.puts("");    // make sure buffer is non-NULL
     while (1) {
         n = recv(sock, buf, 8192, 0);
         if (n <= 0) return ERR_READ;