diff --git a/wsme/rest/json.py b/wsme/rest/json.py
index 0bc29e6..1b567d6 100644
--- a/wsme/rest/json.py
+++ b/wsme/rest/json.py
@@ -11,8 +11,10 @@ from simplegeneric import generic
 
 from wsme.types import Unset
 import wsme.types
+import wsme.utils
 from wsme.exc import UnknownArgument
 
+
 try:
     import simplejson as json
 except ImportError:
@@ -182,21 +184,21 @@ def decimal_fromjson(datatype, value):
 def date_fromjson(datatype, value):
     if value is None:
         return None
-    return datetime.datetime.strptime(value, '%Y-%m-%d').date()
+    return wsme.utils.parse_isodate(value)
 
 
 @fromjson.when_object(datetime.time)
 def time_fromjson(datatype, value):
     if value is None:
         return None
-    return datetime.datetime.strptime(value, '%H:%M:%S').time()
+    return wsme.utils.parse_isotime(value)
 
 
 @fromjson.when_object(datetime.datetime)
 def datetime_fromjson(datatype, value):
     if value is None:
         return None
-    return datetime.datetime.strptime(value, '%Y-%m-%dT%H:%M:%S')
+    return wsme.utils.parse_isodatetime(value)
 
 
 def parse(s, datatypes, bodyarg, encoding='utf8'):
diff --git a/wsme/rest/xml.py b/wsme/rest/xml.py
index 01ffaed..eb8ce7e 100644
--- a/wsme/rest/xml.py
+++ b/wsme/rest/xml.py
@@ -213,26 +213,21 @@ def unicode_fromxml(datatype, element):
 def date_fromxml(datatype, element):
     if element.get('nil') == 'true':
         return None
-    return datetime.datetime.strptime(element.text, '%Y-%m-%d').date()
+    return wsme.utils.parse_isodate(element.text)
 
 
 @fromxml.when_object(datetime.time)
 def time_fromxml(datatype, element):
     if element.get('nil') == 'true':
         return None
-    m = time_re.match(element.text)
-    if m:
-        return datetime.time(
-            int(m.group('h')),
-            int(m.group('m')),
-            int(m.group('s')))
+    return wsme.utils.parse_isotime(element.text)
 
 
 @fromxml.when_object(datetime.datetime)
 def datetime_fromxml(datatype, element):
     if element.get('nil') == 'true':
         return None
-    return datetime.datetime.strptime(element.text, '%Y-%m-%dT%H:%M:%S')
+    return wsme.utils.parse_isodatetime(element.text)
 
 
 def parse(s, datatypes, bodyarg):