diff --git a/test/test_wsgi_compliance.py b/test/test_wsgi_compliance.py
index faf7dab..654b23c 100644
--- a/test/test_wsgi_compliance.py
+++ b/test/test_wsgi_compliance.py
@@ -50,7 +50,8 @@ def test_more_interesting():
         resp, content = http.request(
             'http://some_hopefully_nonexistant_domain' + expected_uri,
             'GET',
-            headers={'Accept': 'application/json'})
+            headers={'Accept': 'application/json',
+                     'Cookie': 'foo=bar'})
         internal_env = app.get_internals()
 
         expected_path_info = unquote(expected_uri.split('?')[0])
@@ -58,6 +59,8 @@ def test_more_interesting():
         assert internal_env['RAW_URI'] == expected_uri
         assert internal_env['QUERY_STRING'] == 'bar=baz%20zoom'
         assert internal_env['HTTP_ACCEPT'] == 'application/json'
+        assert internal_env['HTTP_COOKIE'] == 'foo=bar'
+        assert type(internal_env['HTTP_COOKIE']) == type('')
 
         # Do the rather painful wsgi encoding dance.
         if sys.version_info[0] > 2:
diff --git a/wsgi_intercept/__init__.py b/wsgi_intercept/__init__.py
index 6e20744..3ad0a86 100644
--- a/wsgi_intercept/__init__.py
+++ b/wsgi_intercept/__init__.py
@@ -220,7 +220,11 @@ def make_environ(inp, host, port, script_name):
 
         k, v = line.strip().split(b':', 1)
         v = v.lstrip()
-        v = v.decode('ISO-8859-1')
+        # Make header value a "native" string. PEP 3333 requires that
+        # string-like things in headers be of type `str`. Much of the
+        # time this isn't a problem but the SimpleCookie library does
+        # type checking against `type("")`.
+        v = str(v.decode('ISO-8859-1'))
 
         #
         # take care of special headers, and for the rest, put them