diff --git a/rest_framework/authentication.py b/rest_framework/authentication.py
index 0ca90873e..0cd2dd0db 100644
--- a/rest_framework/authentication.py
+++ b/rest_framework/authentication.py
@@ -19,7 +19,7 @@ def get_authorization_header(request):
     Hide some test client ickyness where the header can be unicode.
     """
     auth = request.META.get('HTTP_AUTHORIZATION', b'')
-    if isinstance(auth, type('')):
+    if isinstance(auth, str):
         # Work around django test client oddness
         auth = auth.encode(HTTP_HEADER_ENCODING)
     return auth