diff --git a/src/osgEarthDrivers/engine_rex/DrawState.cpp b/src/osgEarthDrivers/engine_rex/DrawState.cpp
index ba43f2ea74..c389578499 100644
--- a/src/osgEarthDrivers/engine_rex/DrawState.cpp
+++ b/src/osgEarthDrivers/engine_rex/DrawState.cpp
@@ -39,22 +39,28 @@ ProgramState::init(
     // Size the sampler states property:
     _samplerState._samplers.resize(bindings->size());
 
-    // for each sampler binding, initialize its state tracking structure 
+    // for each sampler binding, initialize its state tracking structure
     // and resolve its matrix uniform location:
     for (unsigned i = 0; i < bindings->size(); ++i)
     {
         const SamplerBinding& binding = (*bindings)[i];
         _samplerState._samplers[i]._name = binding.samplerName();
-        _samplerState._samplers[i]._matrixUL = _pcp->getUniformLocation(
-            osg::Uniform::getNameID(binding.matrixName()));
+        if (_pcp)
+        {
+            _samplerState._samplers[i]._matrixUL = _pcp->getUniformLocation(
+                osg::Uniform::getNameID(binding.matrixName()));
+        }
     }
 
     // resolve all the other uniform locations:
-    _tileKeyUL = _pcp->getUniformLocation(osg::Uniform::getNameID("oe_tile_key_u"));
-    _parentTextureExistsUL = _pcp->getUniformLocation(osg::Uniform::getNameID("oe_layer_texParentExists"));
-    _layerUidUL = _pcp->getUniformLocation(osg::Uniform::getNameID("oe_layer_uid"));
-    _layerOrderUL = _pcp->getUniformLocation(osg::Uniform::getNameID("oe_layer_order"));
-    _morphConstantsUL = _pcp->getUniformLocation(osg::Uniform::getNameID("oe_tile_morph"));
+    if (_pcp)
+    {
+        _tileKeyUL = _pcp->getUniformLocation(osg::Uniform::getNameID("oe_tile_key_u"));
+        _parentTextureExistsUL = _pcp->getUniformLocation(osg::Uniform::getNameID("oe_layer_texParentExists"));
+        _layerUidUL = _pcp->getUniformLocation(osg::Uniform::getNameID("oe_layer_uid"));
+        _layerOrderUL = _pcp->getUniformLocation(osg::Uniform::getNameID("oe_layer_order"));
+        _morphConstantsUL = _pcp->getUniformLocation(osg::Uniform::getNameID("oe_tile_morph"));
+    }
 
     // Reset all optional states
     reset();