diff --git a/tests/widget_lib/widget_lib/example.py b/tests/widget_lib/widget_lib/example.py
index 0af23b9ff..4acf3f2eb 100644
--- a/tests/widget_lib/widget_lib/example.py
+++ b/tests/widget_lib/widget_lib/example.py
@@ -45,4 +45,4 @@ class ModuleImportError(DOMWidget):
 
 
 class WrongVersion(Button):
-    _model_module_version = Unicode('0.0').tag(sync=True)
\ No newline at end of file
+    _model_module_version = Unicode('0.0').tag(sync=True)