diff --git a/swift/common/constraints.py b/swift/common/constraints.py
index eacc6c8d32..a437b32924 100644
--- a/swift/common/constraints.py
+++ b/swift/common/constraints.py
@@ -306,7 +306,8 @@ def check_utf8(string):
         if isinstance(string, unicode):
             string.encode('utf-8')
         else:
-            string.decode('UTF-8')
+            if string.decode('UTF-8').encode('UTF-8') != string:
+                return False
         return '\x00' not in string
     # If string is unicode, decode() will raise UnicodeEncodeError
     # So, we should catch both UnicodeDecodeError & UnicodeEncodeError
diff --git a/test/unit/common/test_constraints.py b/test/unit/common/test_constraints.py
index 8f17ec7e4c..d7f332d9b1 100644
--- a/test/unit/common/test_constraints.py
+++ b/test/unit/common/test_constraints.py
@@ -416,6 +416,10 @@ class TestConstraints(unittest.TestCase):
                               valid_utf8_str]:
             self.assertTrue(constraints.check_utf8(true_argument))
 
+    def test_check_utf8_non_canonical(self):
+        self.assertFalse(constraints.check_utf8('\xed\xa0\xbc\xed\xbc\xb8'))
+        self.assertFalse(constraints.check_utf8('\xed\xa0\xbd\xed\xb9\x88'))
+
     def test_validate_bad_meta(self):
         req = Request.blank(
             '/v/a/c/o',