use !r for explicit_text in NoticeReference repr
diff --git a/src/cryptography/x509.py b/src/cryptography/x509.py
index b559ae0..0227765 100644
--- a/src/cryptography/x509.py
+++ b/src/cryptography/x509.py
@@ -525,7 +525,7 @@
     def __repr__(self):
         return (
             "<UserNotice(notice_reference={0.notice_reference}, explicit_text="
-            "{0.explicit_text})>".format(self)
+            "{0.explicit_text!r})>".format(self)
         )
 
     notice_reference = utils.read_only_property("_notice_reference")
diff --git a/tests/test_x509_ext.py b/tests/test_x509_ext.py
index 10afa1b..fa025d9 100644
--- a/tests/test_x509_ext.py
+++ b/tests/test_x509_ext.py
@@ -71,7 +71,7 @@
         un = x509.UserNotice(x509.NoticeReference("org", None), "text")
         assert repr(un) == (
             "<UserNotice(notice_reference=<NoticeReference(organization=org, "
-            "notice_numbers=None)>, explicit_text=text)>"
+            "notice_numbers=None)>, explicit_text='text')>"
         )
 
 
@@ -102,13 +102,13 @@
             assert repr(pi) == (
                 "<PolicyInformation(policy_identifier=<ObjectIdentifier(oid=1."
                 "2.3, name=Unknown OID)>, policy_qualifiers=['string', <UserNo"
-                "tice(notice_reference=None, explicit_text=hi)>])>"
+                "tice(notice_reference=None, explicit_text='hi')>])>"
             )
         else:
             assert repr(pi) == (
                 "<PolicyInformation(policy_identifier=<ObjectIdentifier(oid=1."
                 "2.3, name=Unknown OID)>, policy_qualifiers=[u'string', <UserN"
-                "otice(notice_reference=None, explicit_text=hi)>])>"
+                "otice(notice_reference=None, explicit_text='hi')>])>"
             )