diff --git a/setup.py b/setup.py
index cd5825c..498a8b0 100755
--- a/setup.py
+++ b/setup.py
@@ -11,10 +11,10 @@
       url="http://singer.io",
       install_requires=[
           'pytz>=2018.4',
-          'jsonschema==2.6.0',
-          'simplejson==3.11.1',
+          'jsonschema>=2.6.0',
+          'simplejson>=3.11.1',
           'python-dateutil>=2.6.0',
-          'backoff==1.8.0',
+          'backoff>=1.8.0',
 	  'ciso8601',
       ],
       extras_require={
diff --git a/singer/utils.py b/singer/utils.py
index 492e03b..af000a4 100644
--- a/singer/utils.py
+++ b/singer/utils.py
@@ -5,7 +5,7 @@
 import json
 import time
 from warnings import warn
-
+import ciso8601
 import dateutil.parser
 import pytz
 import backoff as backoff_module
@@ -58,7 +58,8 @@ def strptime(dtime):
     return datetime.datetime.strptime(dtime, DATETIME_PARSE)
 
 def strptime_to_utc(dtimestr):
-    d_object = dateutil.parser.parse(dtimestr)
+    # d_object = dateutil.parser.parse(dtimestr)
+    d_object = ciso8601.parse_datetime(dtimestr)
     if d_object.tzinfo is None:
         return d_object.replace(tzinfo=pytz.UTC)
     else: