diff --git a/test/systemvm/__init__.py b/test/systemvm/__init__.py
index b47c4766bf0..858bc5fd47a 100644
--- a/test/systemvm/__init__.py
+++ b/test/systemvm/__init__.py
@@ -41,7 +41,7 @@ except (NameError, ImportError):
             error.output = output
             raise error
         return output
-    subprocess.check_output
+    subprocess.check_output = check_output
 
 
 from vagrant import Vagrant