diff --git a/.travis.yml b/.travis.yml
index 2ad132c..32556f0 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,7 +6,7 @@ branches:
         
 python:
     - "2.7"
-    - "3.3"
+    - "3.4"
     - "3.5"
     - "3.6"
 install:
diff --git a/CHANGES.md b/CHANGES.md
index a21423d..012ee11 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,5 +1,10 @@
 ## Changes
 
+### 0.8.38
+
+- Allow to access headers with case insensitive keys
+- Drop support to py3.3 because of Tornado
+
 ### 0.8.37
 
 - Fix loading error on 'yaml' document
diff --git a/pyswagger/__init__.py b/pyswagger/__init__.py
index 0b87652..616c029 100644
--- a/pyswagger/__init__.py
+++ b/pyswagger/__init__.py
@@ -1,4 +1,4 @@
-__version__ = '0.8.37'
+__version__ = '0.8.38'
 
 from .getter import Getter
 from .core import App, Security
diff --git a/pyswagger/io.py b/pyswagger/io.py
index 9852ff5..6fdb78d 100644
--- a/pyswagger/io.py
+++ b/pyswagger/io.py
@@ -1,6 +1,6 @@
 from __future__ import absolute_import
 from .primitives.comm import PrimJSONEncoder
-from .utils import final, deref
+from .utils import final, deref, CaseInsensitiveDict
 from pyswagger import errs
 from uuid import uuid4
 import six
@@ -33,7 +33,7 @@ def __init__(self, op, params):
         self.__p = params
         self.__url = self.__op.url
         self.__path = self.__op.path
-        self.__header = {}
+        self.__header = CaseInsensitiveDict()
 
         self.__consume = None
         self.__produce = None
@@ -42,7 +42,7 @@ def __init__(self, op, params):
     def reset(self):
         self.__url = self.__op.url
         self.__path = self.__op.path
-        self.__header = {}
+        self.__header = CaseInsensitiveDict()
         self.__data = None
 
     def consume(self, consume):
@@ -350,7 +350,7 @@ def __init__(self, op):
 
         # init properties
         self.__status = None
-        self.__header = {}
+        self.__header = CaseInsensitiveDict()
 
         # options
         self.__raw_body_only = False
diff --git a/pyswagger/primitives/__init__.py b/pyswagger/primitives/__init__.py
index 6e2aff1..edac8cd 100644
--- a/pyswagger/primitives/__init__.py
+++ b/pyswagger/primitives/__init__.py
@@ -90,7 +90,11 @@ def __init__(self):
 
     def get(self, _type, _format=None):
         r = self._map.get(_type, None)
-        return (None, None) if r == None else r.get(_format, (None, None))
+        if r is None:
+            return (None, None)
+        if _format in r:
+            return r.get(_format)
+        return r.get(None)
 
     def register(self, _type, _format, creater, _2nd_pass=None):
         """ register a type/format handler when producing primitives
diff --git a/pyswagger/primitives/_model.py b/pyswagger/primitives/_model.py
index 32afd41..087df19 100644
--- a/pyswagger/primitives/_model.py
+++ b/pyswagger/primitives/_model.py
@@ -15,7 +15,7 @@ def __init__(self):
         super(Model, self).__init__()
 
     def apply_with(self, obj, val, ctx):
-        """ recursivly apply Schema object
+        """ recursively apply Schema object
 
         :param obj.Model obj: model object to instruct how to create this model
         :param dict val: things used to construct this model
diff --git a/pyswagger/primitives/_str.py b/pyswagger/primitives/_str.py
index de9fc22..a60b51b 100644
--- a/pyswagger/primitives/_str.py
+++ b/pyswagger/primitives/_str.py
@@ -10,7 +10,7 @@ def validate_str(obj, ret, val, ctx):
     if obj.maxLength and len(ret) > obj.maxLength:
         raise ValidationError('[{0}] is longer than {1} characters'.format(ret, str(obj.maxLength)))
     if obj.minLength and len(ret) < obj.minLength:
-        raise ValidationError('[{0}] is shoter than {1} characters'.format(ret, str(obj.minLength)))
+        raise ValidationError('[{0}] is shorter than {1} characters'.format(ret, str(obj.minLength)))
 
     # TODO: handle pattern
     return val
diff --git a/pyswagger/tests/test_utils.py b/pyswagger/tests/test_utils.py
index 945a8e5..164beea 100644
--- a/pyswagger/tests/test_utils.py
+++ b/pyswagger/tests/test_utils.py
@@ -429,3 +429,28 @@ def test_multiple_cycles_2(self):
             [2, 3, 5, 4, 2],
             [2, 3 ,4, 2]
             ]))
+
+    def test_case_insensitive_dict(self):
+        """ test utils.CaseInsensitiveDict
+        """
+        normal = utils.CaseInsensitiveDict()
+        normal['Content-Type'] = 'application/json'
+        self.assertTrue('Content-Type' in normal)
+        self.assertTrue('content-type' in normal)
+        self.assertEqual(normal['content-type'], 'application/json')
+
+        # test iteration
+        for k, v in normal.iteritems():
+            self.assertEqual(k, 'Content-Type')
+            self.assertEqual(v, 'application/json')
+            break
+        else:
+            # should not reach here
+            self.assertTrue(False)
+
+        for v in normal.itervalues():
+            self.assertEqual(v, 'application/json')
+            break
+        else:
+            # should not reach here
+            self.assertTrue(False)
diff --git a/pyswagger/utils.py b/pyswagger/utils.py
index 76ce070..485b245 100644
--- a/pyswagger/utils.py
+++ b/pyswagger/utils.py
@@ -9,6 +9,7 @@
 import os
 import operator
 import functools
+import collections
 
 #TODO: accept varg
 def scope_compose(scope, name, sep=private.SCOPE_SEPARATOR):
@@ -593,3 +594,45 @@ def patch_path(base_path, path):
         path = path[1:]
 
     return path
+
+
+class CaseInsensitiveDict(collections.MutableMapping):
+    """ a case insensitive dict:
+        - allow to query with case insensitive keys (get, in)
+        - iteration would return original key
+
+    A reference implementation could be found in
+
+        https://github.com/requests/
+    """
+
+    def __init__(self):
+        self._store = dict()
+
+    def __setitem__(self, key, value):
+        self._store[key.lower()] = (key, value)
+
+    def __getitem__(self, key):
+        return self._store[key.lower()][1]
+
+    def __delitem__(self, key):
+        del self._store[key.lower()]
+
+    def __iter__(self):
+        return (original_key for original_key, _ in six.itervalues(self._store))
+
+    def iteritems(self):
+        return six.itervalues(self._store)
+
+    def itervalues(self):
+        return (value for _, value in six.itervalues(self._store))
+
+    def __in__(self, key):
+        return key.lower() in self._store
+
+    def __len__(self):
+        return len(self._store)
+
+    def __repr__(self):
+        return str(dict(self.items()))
+