diff --git a/source/MaterialXGenShader/Nodes/HwTransformNode.cpp b/source/MaterialXGenShader/Nodes/HwTransformNode.cpp
index 8d7b979d75..018924855d 100644
--- a/source/MaterialXGenShader/Nodes/HwTransformNode.cpp
+++ b/source/MaterialXGenShader/Nodes/HwTransformNode.cpp
@@ -9,11 +9,11 @@
 
 MATERIALX_NAMESPACE_BEGIN
 
-string HwTransformNode::FROM_SPACE = "fromspace";
-string HwTransformNode::TO_SPACE = "tospace";
-string HwTransformNode::MODEL = "model";
-string HwTransformNode::OBJECT = "object";
-string HwTransformNode::WORLD = "world";
+const string HwTransformNode::FROM_SPACE = "fromspace";
+const string HwTransformNode::TO_SPACE = "tospace";
+const string HwTransformNode::MODEL = "model";
+const string HwTransformNode::OBJECT = "object";
+const string HwTransformNode::WORLD = "world";
 
 void HwTransformNode::createVariables(const ShaderNode& node, GenContext&, Shader& shader) const
 {
diff --git a/source/MaterialXGenShader/Nodes/HwTransformNode.h b/source/MaterialXGenShader/Nodes/HwTransformNode.h
index fe29f27a43..a97e57405c 100644
--- a/source/MaterialXGenShader/Nodes/HwTransformNode.h
+++ b/source/MaterialXGenShader/Nodes/HwTransformNode.h
@@ -27,11 +27,11 @@ class MX_GENSHADER_API HwTransformNode : public ShaderNodeImpl
     virtual string getFromSpace(const ShaderNode&) const;
     virtual string getToSpace(const ShaderNode&) const;
 
-    static string FROM_SPACE;
-    static string TO_SPACE;
-    static string MODEL;
-    static string OBJECT;
-    static string WORLD;
+    static const string FROM_SPACE;
+    static const string TO_SPACE;
+    static const string MODEL;
+    static const string OBJECT;
+    static const string WORLD;
 };
 
 class MX_GENSHADER_API HwTransformVectorNode : public HwTransformNode