diff --git a/source/include/signalflow/core/graph.h b/source/include/signalflow/core/graph.h
index dfe6c240..dbdcf428 100644
--- a/source/include/signalflow/core/graph.h
+++ b/source/include/signalflow/core/graph.h
@@ -23,7 +23,7 @@ class AudioGraph
 {
 public:
     AudioGraph(AudioGraphConfig *config = nullptr, std::string output_device = "", bool start = true);
-    AudioGraph(AudioGraphConfig *config = nullptr, NodeRef output_device = nullptr, bool start = true);
+    AudioGraph(AudioGraphConfig *config, NodeRef output_device, bool start = true);
 
     virtual ~AudioGraph();