diff --git a/src/osg/Drawable.cpp b/src/osg/Drawable.cpp
index 0a77f03c0..bff5a80e3 100644
--- a/src/osg/Drawable.cpp
+++ b/src/osg/Drawable.cpp
@@ -843,6 +843,7 @@ Drawable::Extensions::Extensions(const Extensions& rhs):
     _isFogCoordSupported = rhs._isFogCoordSupported;
     _isMultiTexSupported = rhs._isMultiTexSupported;
     _isOcclusionQuerySupported = rhs._isOcclusionQuerySupported;
+    _isARBOcclusionQuerySupported = rhs._isARBOcclusionQuerySupported;
     _isTimerQuerySupported = rhs._isTimerQuerySupported;
     _isARBTimerQuerySupported = rhs._isARBTimerQuerySupported;