diff --git a/src/EthernetClient.cpp b/src/EthernetClient.cpp
index 70bb01d..5941afd 100644
--- a/src/EthernetClient.cpp
+++ b/src/EthernetClient.cpp
@@ -195,6 +195,7 @@ void EthernetClient::stop()
     tcp_connection_close(_tcp_client->pcb, _tcp_client);
   }
   mem_free(_tcp_client);
+  _tcp_client = NULL;
 }
 
 uint8_t EthernetClient::connected()