diff --git a/features/netsocket/InternetSocket.cpp b/features/netsocket/InternetSocket.cpp
index cd79f0668f..a114b6bbf9 100644
--- a/features/netsocket/InternetSocket.cpp
+++ b/features/netsocket/InternetSocket.cpp
@@ -62,6 +62,7 @@ nsapi_error_t InternetSocket::close()
 
     nsapi_error_t ret = NSAPI_ERROR_OK;
     if (!_socket)  {
+        _lock.unlock();
         return NSAPI_ERROR_NO_SOCKET;
     }