diff --git a/jsonschema/_utils.py b/jsonschema/_utils.py
index 5b245a34a..9564d0241 100644
--- a/jsonschema/_utils.py
+++ b/jsonschema/_utils.py
@@ -101,7 +101,10 @@ 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):
+            prop = property
+            if not isinstance(prop, str):
+                prop = str(property)
+            if patterns and re.search(patterns, prop):
                 continue
             yield property
 
diff --git a/jsonschema/_validators.py b/jsonschema/_validators.py
index d0baec812..1c8bb72a3 100644
--- a/jsonschema/_validators.py
+++ b/jsonschema/_validators.py
@@ -11,7 +11,7 @@ def patternProperties(validator, patternProperties, instance, schema):
 
     for pattern, subschema in iteritems(patternProperties):
         for k, v in iteritems(instance):
-            if re.search(pattern, k):
+            if re.search(pattern, str(k)):
                 for error in validator.descend(
                     v, subschema, path=k, schema_path=pattern,
                 ):