diff --git a/components/sceneutil/lightcontroller.cpp b/components/sceneutil/lightcontroller.cpp
index 511937a28..e3ea93843 100644
--- a/components/sceneutil/lightcontroller.cpp
+++ b/components/sceneutil/lightcontroller.cpp
@@ -125,7 +125,7 @@ namespace SceneUtil
         traverse(node, nv);
     }
 
-    void LightController::setDiffuse(osg::Vec4f color)
+    void LightController::setDiffuse(const osg::Vec4f& color)
     {
         mDiffuseColor = color;
     }
diff --git a/components/sceneutil/lightcontroller.hpp b/components/sceneutil/lightcontroller.hpp
index f6e2fa9fa..8f70af343 100644
--- a/components/sceneutil/lightcontroller.hpp
+++ b/components/sceneutil/lightcontroller.hpp
@@ -24,7 +24,7 @@ namespace SceneUtil
 
         void setType(LightType type);
 
-        void setDiffuse(osg::Vec4f color);
+        void setDiffuse(const osg::Vec4f& color);
 
         virtual void operator()(osg::Node* node, osg::NodeVisitor* nv);