diff --git a/jsonschema/_utils.py b/jsonschema/_utils.py
index 2262f3305..c4472332b 100644
--- a/jsonschema/_utils.py
+++ b/jsonschema/_utils.py
@@ -2,10 +2,17 @@
 import json
 import pkgutil
 import re
+import sys
 
 from jsonschema.compat import str_types, MutableMapping, urlsplit
 
 
+if sys.version_info[0] == 3:
+    STRING_TYPES = str
+else:
+    STRING_TYPES = (str, unicode)
+
+
 class URIDict(MutableMapping):
     """
     Dictionary which uses normalized URIs as keys.
@@ -97,7 +104,7 @@ def find_additional_properties(instance, schema):
     patterns = "|".join(schema.get("patternProperties", {}))
     for property in instance:
         if property not in properties:
-            if patterns and re.search(patterns, property):
+            if isinstance(property, STRING_TYPES) and patterns and re.search(patterns, property):
                 continue
             yield property
 
diff --git a/jsonschema/_validators.py b/jsonschema/_validators.py
index c6e801ccb..5eed8a564 100644
--- a/jsonschema/_validators.py
+++ b/jsonschema/_validators.py
@@ -1,6 +1,7 @@
 import re
 
 from jsonschema import _utils
+from jsonschema._utils import STRING_TYPES
 from jsonschema.exceptions import FormatError, ValidationError
 from jsonschema.compat import iteritems
 
@@ -14,7 +15,7 @@ def patternProperties(validator, patternProperties, instance, schema):
 
     for pattern, subschema in iteritems(patternProperties):
         for k, v in iteritems(instance):
-            if re.search(pattern, k):
+            if isinstance(k, STRING_TYPES) and re.search(pattern, k):
                 for error in validator.descend(
                     v, subschema, path=k, schema_path=pattern,
                 ):
diff --git a/jsonschema/tests/test_validators.py b/jsonschema/tests/test_validators.py
index f8692388e..b877585ca 100644
--- a/jsonschema/tests/test_validators.py
+++ b/jsonschema/tests/test_validators.py
@@ -777,6 +777,26 @@ def test_if_you_give_it_junk_you_get_a_resolution_error(self):
         self.assertEqual(str(err.exception), "Oh no! What's this?")
 
 
+class TestSimpleBug(unittest.TestCase):
+    def test_non_string_object_key(self):
+        schema = {
+            "type": "object",
+            "patternProperties": {
+                ".*": {
+                    "type": "string",
+                },
+            },
+            "additionalProperties": False,
+        }
+
+        obj = {
+            42: True,
+        }
+
+        with self.assertRaises(ValidationError):
+            validate(obj, schema)
+
+
 def sorted_errors(errors):
     def key(error):
         return (