diff --git a/letsencrypt/acme/util.py b/letsencrypt/acme/util.py
index e325d07e2..1dd7ac78e 100644
--- a/letsencrypt/acme/util.py
+++ b/letsencrypt/acme/util.py
@@ -123,5 +123,5 @@ class ImmutableMap(object):  # pylint: disable=too-few-public-methods
 
     def __repr__(self):
         return '{0}({1})'.format(self.__class__.__name__, ', '.join(
-            '{0}={1}'.format(slot, getattr(self, slot))
+            '{0}={1!r}'.format(slot, getattr(self, slot))
             for slot in self.__slots__))
diff --git a/letsencrypt/acme/util_test.py b/letsencrypt/acme/util_test.py
index 42297de89..cf71963e8 100644
--- a/letsencrypt/acme/util_test.py
+++ b/letsencrypt/acme/util_test.py
@@ -160,6 +160,7 @@ class ImmutableMapTest(unittest.TestCase):
         self.assertEqual('A(x=1, y=2)', repr(self.a1))
         self.assertEqual('A(x=1, y=2)', repr(self.a1_swap))
         self.assertEqual('B(x=1, y=2)', repr(self.b))
+        self.assertEqual("B(x='foo', y='bar')", repr(self.B(x='foo', y='bar')))
 
 
 if __name__ == '__main__':