diff --git a/contrib/zeromq/TZmqServer.cpp b/contrib/zeromq/TZmqServer.cpp
index 88660a3..1ad7db8 100644
--- a/contrib/zeromq/TZmqServer.cpp
+++ b/contrib/zeromq/TZmqServer.cpp
@@ -41,7 +41,7 @@
       outputProtocolFactory_->getProtocol(outputTransport));
   shared_ptr<TMemoryBuffer> transport(new TMemoryBuffer);
 
-  processor_->process(inputProtocol, outputProtocol, NULL);
+  processor_->process(inputProtocol, outputProtocol, nullptr);
 
   if (zmq_type_ == ZMQ_REP) {
     uint8_t* buf;