diff --git a/Libraries/Opc.Ua.Server/Diagnostics/CustomNodeManager.cs b/Libraries/Opc.Ua.Server/Diagnostics/CustomNodeManager.cs
index 7619d9502..1a5668ed5 100644
--- a/Libraries/Opc.Ua.Server/Diagnostics/CustomNodeManager.cs
+++ b/Libraries/Opc.Ua.Server/Diagnostics/CustomNodeManager.cs
@@ -107,6 +107,8 @@ protected CustomNodeManager2(
             // create the table of monitored nodes.
             // these are created by the node manager whenever a client subscribe to an attribute of the node.
             m_monitoredNodes = new NodeIdDictionary<MonitoredNode2>();
+
+            m_predefinedNodes = new NodeIdDictionary<NodeState>();
         }
         #endregion
 
@@ -129,7 +131,7 @@ protected virtual void Dispose(bool disposing)
             {
                 lock (Lock)
                 {
-                    foreach (NodeState node in m_predefinedNodes?.Values)
+                    foreach (NodeState node in m_predefinedNodes.Values)
                     {
                         Utils.SilentDispose(node);
                     }
@@ -321,7 +323,7 @@ protected virtual NodeHandle IsHandleInNamespace(object managerHandle)
         public NodeState Find(NodeId nodeId)
         {
             NodeState node = null;
-            if (m_predefinedNodes?.TryGetValue(nodeId, out node) == true)
+            if (m_predefinedNodes.TryGetValue(nodeId, out node) == true)
             {
                 return node;
             }
@@ -349,11 +351,6 @@ public NodeId CreateNode(
 
             lock (Lock)
             {
-                if (m_predefinedNodes == null)
-                {
-                    m_predefinedNodes = new NodeIdDictionary<NodeState>();
-                }
-
                 instance.ReferenceTypeId = referenceTypeId;
 
                 NodeState parent = null;
@@ -390,7 +387,7 @@ public bool DeleteNode(
             List<LocalReference> referencesToRemove = new List<LocalReference>();
 
             NodeState node = null;
-            if (m_predefinedNodes?.TryGetValue(nodeId, out node) != true)
+            if (m_predefinedNodes.TryGetValue(nodeId, out node) != true)
             {
                 return false;
             }
@@ -477,11 +474,6 @@ public virtual void LoadPredefinedNodes(
             string resourcePath,
             IDictionary<NodeId, IList<IReference>> externalReferences)
         {
-            if (m_predefinedNodes == null)
-            {
-                m_predefinedNodes = new NodeIdDictionary<NodeState>();
-            }
-
             // load the predefined nodes from an XML document.
             NodeStateCollection predefinedNodes = new NodeStateCollection();
             predefinedNodes.LoadFromResource(context, resourcePath, assembly, true);
@@ -544,11 +536,6 @@ protected virtual NodeState AddBehaviourToPredefinedNode(ISystemContext context,
         /// </summary>
         protected virtual void AddPredefinedNode(ISystemContext context, NodeState node)
         {
-            if (m_predefinedNodes == null)
-            {
-                m_predefinedNodes = new NodeIdDictionary<NodeState>();
-            }
-
             // assign a default value to any variable in namespace 0
             if (node is BaseVariableState nodeStateVar)
             {
@@ -614,7 +601,7 @@ protected virtual void RemovePredefinedNode(
             NodeState node,
             List<LocalReference> referencesToRemove)
         {
-            if (m_predefinedNodes?.TryRemove(node.NodeId, out _) != true)
+            if (m_predefinedNodes.TryRemove(node.NodeId, out _) != true)
             {
                 return;
             }
@@ -687,7 +674,7 @@ protected virtual void OnNodeRemoved(NodeState node)
         /// <param name="externalReferences">A list of references to add to external targets.</param>
         protected virtual void AddReverseReferences(IDictionary<NodeId, IList<IReference>> externalReferences)
         {
-            foreach (NodeState source in m_predefinedNodes?.Values)
+            foreach (NodeState source in m_predefinedNodes.Values)
             {
                 IList<IReference> references = new List<IReference>();
                 source.GetReferences(SystemContext, references);
@@ -855,15 +842,12 @@ public NodeState FindPredefinedNode(NodeId nodeId, Type expectedType)
         /// </summary>
         public virtual void DeleteAddressSpace()
         {
-            if (m_predefinedNodes != null)
-            {
-                var nodes = m_predefinedNodes.Values.ToArray();
-                m_predefinedNodes.Clear();
+            var nodes = m_predefinedNodes.Values.ToArray();
+            m_predefinedNodes.Clear();
 
-                foreach (NodeState node in nodes)
-                {
-                    Utils.SilentDispose(node);
-                }
+            foreach (NodeState node in nodes)
+            {
+                Utils.SilentDispose(node);
             }
         }
 
@@ -894,7 +878,7 @@ protected virtual NodeHandle GetManagerHandle(ServerSystemContext context, NodeI
             }
 
             NodeState node = null;
-            if (m_predefinedNodes?.TryGetValue(nodeId, out node) == true)
+            if (m_predefinedNodes.TryGetValue(nodeId, out node) == true)
             {
                 var handle = new NodeHandle {
                     NodeId = nodeId,