Index: /pyyaml/trunk/lib/yaml/constructor.py
===================================================================
--- /pyyaml/trunk/lib/yaml/constructor.py	(revision 258)
+++ /pyyaml/trunk/lib/yaml/constructor.py	(revision 269)
@@ -322,5 +322,8 @@
         fraction = 0
         if values['fraction']:
-            fraction = int(values['fraction'][:6].ljust(6, '0'))
+            fraction = values['fraction'][:6]
+            while len(fraction) < 6:
+                fraction += '0'
+            fraction = int(fraction)
         delta = None
         if values['tz_sign']: