diff --git a/isso/tests/test_utils.py b/isso/tests/test_utils.py
index 253328c..6a98fe1 100644
--- a/isso/tests/test_utils.py
+++ b/isso/tests/test_utils.py
@@ -19,6 +19,18 @@ class TestUtils(unittest.TestCase):
         for (addr, anonymized) in examples:
             self.assertEqual(utils.anonymize(addr), anonymized)
 
+    def test_str(self):
+        # Accept a str on both Python 2 and Python 3, for
+        # convenience.
+        examples = [
+            ('12.34.56.78', u'12.34.56.0'),
+            ('1234:5678:90ab:cdef:fedc:ba09:8765:4321',
+             '1234:5678:90ab:0000:0000:0000:0000:0000'),
+            ('::ffff:127.0.0.1', u'127.0.0.0')]
+
+        for (addr, anonymized) in examples:
+            self.assertEqual(utils.anonymize(addr), anonymized)
+
 
 class TestParse(unittest.TestCase):
 
diff --git a/isso/utils/__init__.py b/isso/utils/__init__.py
index ed925a9..dc3637a 100644
--- a/isso/utils/__init__.py
+++ b/isso/utils/__init__.py
@@ -14,6 +14,7 @@ from jinja2 import Environment, FileSystemLoader
 from werkzeug.wrappers import Response
 from werkzeug.exceptions import BadRequest
 
+from isso.compat import text_type
 from isso.wsgi import Request
 
 try:
@@ -28,6 +29,8 @@ def anonymize(remote_addr):
     and /48 (zero'd).
 
     """
+    if not isinstance(remote_addr, text_type) and isinstance(remote_addr, str):
+        remote_addr = remote_addr.decode('ascii', 'ignore')
     try:
         ipv4 = ipaddress.IPv4Address(remote_addr)
         return u''.join(ipv4.exploded.rsplit('.', 1)[0]) + '.' + '0'
@@ -35,7 +38,7 @@ def anonymize(remote_addr):
         try:
             ipv6 = ipaddress.IPv6Address(remote_addr)
             if ipv6.ipv4_mapped is not None:
-                return anonymize(ipv6.ipv4_mapped)
+                return anonymize(text_type(ipv6.ipv4_mapped))
             return u'' + ipv6.exploded.rsplit(':', 5)[0] + ':' + ':'.join(['0000'] * 5)
         except ipaddress.AddressValueError:
             return u'0.0.0.0'