diff --git a/support/testing/tests/package/sample_python_crossbar.py b/support/testing/tests/package/sample_python_crossbar.py
index 3695fe92c0..374cccd837 100644
--- a/support/testing/tests/package/sample_python_crossbar.py
+++ b/support/testing/tests/package/sample_python_crossbar.py
@@ -1,3 +1,5 @@
+import os
 import crossbar
 
+os.environ["AUTOBAHN_USE_UMSGPACK"] = "1"
 crossbar.run(["version"])