diff --git a/renderdocui/Windows/BufferViewer.cs b/renderdocui/Windows/BufferViewer.cs
index 2f28ab6f9..f4479c0b0 100644
--- a/renderdocui/Windows/BufferViewer.cs
+++ b/renderdocui/Windows/BufferViewer.cs
@@ -813,7 +813,7 @@ namespace renderdocui.Windows
 
             Input ret = new Input();
             ret.Drawcall = draw;
-            ret.Topology = draw.topology;
+            ret.Topology = draw != null ? draw.topology : PrimitiveTopology.Unknown;
 
             ResourceId ibuffer = ResourceId.Null;
             ulong ioffset = 0;