diff --git a/axes/utils.py b/axes/utils.py
index 0ea87ea..cc88241 100644
--- a/axes/utils.py
+++ b/axes/utils.py
@@ -18,3 +18,24 @@ def reset(ip=None, username=None):
         attempts.delete()
 
     return count
+
+
+def iso8601(value):
+    """Returns datetime.timedelta translated to ISO 8601 formatted duration.
+    """
+    seconds = value.total_seconds()
+    minutes, seconds = divmod(seconds, 60)
+    hours, minutes = divmod(minutes, 60)
+    days, hours = divmod(hours, 24)
+
+    date = '{:.0f}D'.format(days) if days else ''
+
+    time_values = hours, minutes, seconds
+    time_designators = 'H', 'M', 'S'
+
+    time = ''.join(
+        [('{:.0f}'.format(value) + designator)
+        for value, designator in zip(time_values, time_designators)
+        if value]
+    )
+    return u'P' + date + time