diff --git a/renderdoc/driver/d3d11/d3d11_shaderdebug.cpp b/renderdoc/driver/d3d11/d3d11_shaderdebug.cpp
index d7f54f8f9..e3c4643d9 100644
--- a/renderdoc/driver/d3d11/d3d11_shaderdebug.cpp
+++ b/renderdoc/driver/d3d11/d3d11_shaderdebug.cpp
@@ -1977,7 +1977,7 @@ ShaderDebugTrace *D3D11Replay::DebugVertex(uint32_t eventId, uint32_t vertid, ui
       }
       else
       {
-        if(size_t(fmt.compByteWidth * fmt.compCount) > dataSize)
+        if(srcData == NULL || size_t(fmt.compByteWidth * fmt.compCount) > dataSize)
         {
           state.inputs[i].value.u.x = state.inputs[i].value.u.y = state.inputs[i].value.u.z = 0;
           if(fmt.compType == CompType::UInt || fmt.compType == CompType::SInt)