diff --git a/include/osg/LightSource b/include/osg/LightSource
index fccaf1db4..166876039 100644
--- a/include/osg/LightSource
+++ b/include/osg/LightSource
@@ -73,6 +73,9 @@ class OSG_EXPORT LightSource : public Group
         /** Set up the local StateSet. */
         void setLocalStateSetModes(StateAttribute::GLModeValue value = StateAttribute::ON);
 
+        /** Set whether to use a mutex to ensure ref() and unref() are thread safe.*/
+        virtual void setThreadSafeRefUnref(bool threadSafe);
+
         virtual BoundingSphere computeBound() const;
 
     protected:
diff --git a/src/osg/LightSource.cpp b/src/osg/LightSource.cpp
index bfcaf6b0c..451acab20 100644
--- a/src/osg/LightSource.cpp
+++ b/src/osg/LightSource.cpp
@@ -73,3 +73,10 @@ BoundingSphere LightSource::computeBound() const
 
     return bsphere;
 }
+
+void LightSource::setThreadSafeRefUnref(bool threadSafe)
+{
+    Group::setThreadSafeRefUnref(threadSafe);
+
+    if (_light.valid()) _light->setThreadSafeRefUnref(threadSafe);
+}