diff --git a/openstack/common/processutils.py b/openstack/common/processutils.py
index 1aa1335..02cfada 100644
--- a/openstack/common/processutils.py
+++ b/openstack/common/processutils.py
@@ -203,7 +203,7 @@ def trycmd(*args, **kwargs):
     try:
         out, err = execute(*args, **kwargs)
         failed = False
-    except ProcessExecutionError, exn:
+    except ProcessExecutionError as exn:
         out, err = '', str(exn)
         failed = True