diff --git a/libs/backends/coreaudio/coreaudio_backend.h b/libs/backends/coreaudio/coreaudio_backend.h
index 989aeb66ec..950e3fb917 100644
--- a/libs/backends/coreaudio/coreaudio_backend.h
+++ b/libs/backends/coreaudio/coreaudio_backend.h
@@ -429,7 +429,7 @@ class CoreAudioBackend : public AudioBackend, public PortEngineSharedImpl {
 				return *it;
 			}
 		}
-		return NULL;
+		return BackendPortPtr();
 	}
 
 	BackendPort* port_factory (std::string const & name, ARDOUR::DataType type, ARDOUR::PortFlags);