diff --git a/Engine/source/materials/customMaterialDefinition.cpp b/Engine/source/materials/customMaterialDefinition.cpp
index bda6a9afe..b0b6dca4c 100644
--- a/Engine/source/materials/customMaterialDefinition.cpp
+++ b/Engine/source/materials/customMaterialDefinition.cpp
@@ -150,6 +150,8 @@ bool CustomMaterial::onAdd()
                getName(), samplerName.c_str(), mShaderDataName.c_str() ));
             Con::errorf(error);
 
+            pos = i;
+
 #if TORQUE_OPENGL
             GFXAssertFatal(0, error);
             continue;
diff --git a/Engine/source/materials/processedCustomMaterial.cpp b/Engine/source/materials/processedCustomMaterial.cpp
index f2fd7678c..90994af69 100644
--- a/Engine/source/materials/processedCustomMaterial.cpp
+++ b/Engine/source/materials/processedCustomMaterial.cpp
@@ -409,14 +409,14 @@ void ProcessedCustomMaterial::setTextureStages( SceneRenderState *state, const S
                if ( !texObject )
                   texObject = GFXTexHandle::ZERO;
 
-               if ( handles->mRTParamsSC[i]->isValid() && texObject )
+               if ( handles->mRTParamsSC[samplerRegister]->isValid() && texObject )
                {
                   const Point3I &targetSz = texObject->getSize();
                   const RectI &targetVp = texTarget->getViewport();
                   Point4F rtParams;
 
                   ScreenSpace::RenderTargetParameters(targetSz, targetVp, rtParams);
-                  shaderConsts->set(handles->mRTParamsSC[i], rtParams);
+                  shaderConsts->set(handles->mRTParamsSC[samplerRegister], rtParams);
                }
               
                GFX->setTexture( samplerRegister, texObject );