diff --git a/lib/import/BpmnTreeWalker.js b/lib/import/BpmnTreeWalker.js
index 3e666152..e937fad6 100644
--- a/lib/import/BpmnTreeWalker.js
+++ b/lib/import/BpmnTreeWalker.js
@@ -121,7 +121,7 @@ function BpmnTraverser(handler) {
       // force drawing of everything not yet drawn that is part of the target DI
       handleUnhandledProcesses(definitions.rootElements);
     } else {
-      throw new Error('unsupported root element for bpmndi:Diagram: ' + type.name);
+      throw new Error('unsupported root element for bpmndi:Diagram <' + rootElement.$type + '>');
     }
   }