diff --git a/include/osg/ClipPlane b/include/osg/ClipPlane
index c7d96524d..4db9f54e6 100644
--- a/include/osg/ClipPlane
+++ b/include/osg/ClipPlane
@@ -61,7 +61,7 @@ class SG_EXPORT ClipPlane : public StateAttribute
             return 0; // Passed all the above comparison macros, so must be equal.
         }
 
-        virtual unsigned int getMember() { return _clipPlaneNum; }
+        virtual unsigned int getMember() const { return _clipPlaneNum; }
 
         virtual bool getModeUsage(ModeUsage& usage) const
         {
diff --git a/include/osg/Light b/include/osg/Light
index cb85db912..e64fe6cd2 100644
--- a/include/osg/Light
+++ b/include/osg/Light
@@ -67,7 +67,7 @@ class SG_EXPORT Light : public StateAttribute
             return 0; // passed all the above comparison macro's, must be equal.
         }
 
-        virtual unsigned int getMember() { return _lightnum; }
+        virtual unsigned int getMember() const { return _lightnum; }
 
         virtual bool getModeUsage(ModeUsage& usage) const
         {