diff --git a/src/graphnet/models/graphs/graph_definition.py b/src/graphnet/models/graphs/graph_definition.py
index 6366fc390..e384425f9 100644
--- a/src/graphnet/models/graphs/graph_definition.py
+++ b/src/graphnet/models/graphs/graph_definition.py
@@ -24,7 +24,7 @@ class GraphDefinition(Model):
     def __init__(
         self,
         detector: Detector,
-        node_definition: NodeDefinition = NodesAsPulses(),
+        node_definition: NodeDefinition = None,
         edge_definition: Optional[EdgeDefinition] = None,
         input_feature_names: Optional[List[str]] = None,
         dtype: Optional[torch.dtype] = torch.float,
@@ -69,6 +69,9 @@ def __init__(
         # Base class constructor
         super().__init__(name=__name__, class_name=self.__class__.__name__)
 
+        if node_definition is None:
+            node_definition = NodesAsPulses()
+
         # Member Variables
         self._detector = detector
         self._edge_definition = edge_definition