diff --git a/CHANGES b/CHANGES
index 6c0aee747..034b5aecb 100644
--- a/CHANGES
+++ b/CHANGES
@@ -14,6 +14,7 @@ Bugs fixed
 * Remove ``image/gif`` from supported_image_types of LaTeX writer (#2272)
 * Fix code-block literals raises highlighting warnings by default
 * Fix ValueError is raised if LANGUAGE is empty string
+* Fix unpack warning is shown when the directives generated from ``Sphinx.add_crossref_type`` is used
 
 Documentation
 -------------
diff --git a/sphinx/domains/std.py b/sphinx/domains/std.py
index 501d6ea30..e5f9ab557 100644
--- a/sphinx/domains/std.py
+++ b/sphinx/domains/std.py
@@ -121,7 +121,7 @@ class Target(Directive):
                 indextype = indexentry[:colon].strip()
                 indexentry = indexentry[colon+1:].strip()
             inode = addnodes.index(entries=[(indextype, indexentry,
-                                             targetname, '')])
+                                             targetname, '', None)])
             ret.insert(0, inode)
         name = self.name
         if ':' in self.name: