diff --git a/Scripts/Interfaces/INode.cs b/Scripts/Interfaces/INode.cs
index bfbe1e5..82dc762 100644
--- a/Scripts/Interfaces/INode.cs
+++ b/Scripts/Interfaces/INode.cs
@@ -15,8 +15,8 @@ namespace XNode {
         IEnumerable<NodePort> Outputs { get; }
         IEnumerable<NodePort> Inputs { get; }
         IEnumerable<NodePort> InstancePorts { get; }
-        NodePort AddInstanceOutput(Type type, XNode.Node.ConnectionType connectionType = XNode.Node.ConnectionType.Multiple, string fieldName = null);
-        NodePort AddInstanceInput(Type type, XNode.Node.ConnectionType connectionType = XNode.Node.ConnectionType.Multiple, string fieldName = null);
+        NodePort AddDynamicOutput(Type type, XNode.Node.ConnectionType connectionType = XNode.Node.ConnectionType.Multiple, Node.TypeConstraint typeConstraint = Node.TypeConstraint.None, string fieldName = null);
+        NodePort AddDynamicInput(Type type, XNode.Node.ConnectionType connectionType = XNode.Node.ConnectionType.Multiple, Node.TypeConstraint typeConstraint = Node.TypeConstraint.None, string fieldName = null);
         NodePort GetInputPort(string fieldName);
         NodePort GetOutputPort(string fieldName);
         void OnCreateConnection(NodePort from, NodePort to);
diff --git a/Scripts/Node.cs b/Scripts/Node.cs
index 7ba963a..c9fb68b 100644
--- a/Scripts/Node.cs
+++ b/Scripts/Node.cs
@@ -105,7 +105,7 @@ namespace XNode {
         /// <summary> Iterate over all dynamic inputs on this node. </summary>
         public IEnumerable<NodePort> DynamicInputs { get { foreach (NodePort port in Ports) { if (port.IsDynamic && port.IsInput) yield return port; } } }
         /// <summary> Parent <see cref="NodeGraph"/> </summary>
-        public NodeGraph Graph { get { return graph; } }
+        public INodeGraph Graph { get { return graph; } }
         /// <summary> Parent <see cref="NodeGraph"/> </summary>
         [SerializeField] private NodeGraph graph;
         /// <summary> Position on the <see cref="NodeGraph"/> </summary>
diff --git a/Scripts/NodeGraph.cs b/Scripts/NodeGraph.cs
index 6a0cead..a310727 100644
--- a/Scripts/NodeGraph.cs
+++ b/Scripts/NodeGraph.cs
@@ -5,7 +5,7 @@ using UnityEngine;
 namespace XNode {
     /// <summary> Base class for all node graphs </summary>
     [Serializable]
-    public abstract class NodeGraph : ScriptableObject {
+    public abstract class NodeGraph : ScriptableObject, INodeGraph {
 
         /// <summary> All nodes in the graph. <para/>
         /// See: <see cref="AddNode{T}"/> </summary>