diff --git a/glance/common/timeutils.py b/glance/common/timeutils.py
index ea64844a9e..d3d865c3bd 100644
--- a/glance/common/timeutils.py
+++ b/glance/common/timeutils.py
@@ -37,7 +37,8 @@ def isotime(at=None, subsecond=False):
                      if not subsecond
                      else _ISO8601_TIME_FORMAT_SUBSECOND)
     tz = at.tzinfo.tzname(None) if at.tzinfo else 'UTC'
-    st += ('Z' if tz == 'UTC' else tz)
+    # Need to handle either iso8601 or python UTC format
+    st += ('Z' if tz in ['UTC', 'UTC+00:00'] else tz)
     return st