diff --git a/include/osgShadow/ViewDependentShadowMap b/include/osgShadow/ViewDependentShadowMap
index a9f5e717a..70655cd22 100644
--- a/include/osgShadow/ViewDependentShadowMap
+++ b/include/osgShadow/ViewDependentShadowMap
@@ -187,6 +187,7 @@ protected:
         osg::ref_ptr<osg::Texture2D>            _fallbackShadowMapTexture;
 
         typedef std::vector< osg::ref_ptr<osg::Uniform> > Uniforms;
+        mutable OpenThreads::Mutex              _accessUnfiromsAndProgramMutex;
         Uniforms                                _uniforms;
         osg::ref_ptr<osg::Program>              _program;
 };
diff --git a/src/osgShadow/ViewDependentShadowMap.cpp b/src/osgShadow/ViewDependentShadowMap.cpp
index 6f587f9e5..889923e9f 100644
--- a/src/osgShadow/ViewDependentShadowMap.cpp
+++ b/src/osgShadow/ViewDependentShadowMap.cpp
@@ -1161,6 +1161,8 @@ void ViewDependentShadowMap::createShaders()
 
     unsigned int _baseTextureUnit = 0;
 
+    OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_accessUnfiromsAndProgramMutex);
+
     _shadowCastingStateSet = new osg::StateSet;
 
     ShadowSettings* settings = getShadowedScene()->getShadowSettings();
@@ -2342,6 +2344,8 @@ osg::StateSet* ViewDependentShadowMap::selectStateSetForRenderingShadow(ViewDepe
 
     osg::ref_ptr<osg::StateSet> stateset = vdd.getStateSet();
 
+    OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_accessUnfiromsAndProgramMutex);
+    
     vdd.getStateSet()->clear();
 
     vdd.getStateSet()->setTextureAttributeAndModes(0, _fallbackBaseTexture.get(), osg::StateAttribute::ON);