diff --git a/sphinx/directives.py b/sphinx/directives.py
index 3d17d0a10..7d8d8f284 100644
--- a/sphinx/directives.py
+++ b/sphinx/directives.py
@@ -23,8 +23,8 @@ from . import addnodes
 # ------ index markup --------------------------------------------------------------
 
 entrytypes = [
-    'single', 'pair', 'triple', 'quadruple',
-    'module', 'keyword', 'operator', 'object', 'exception', 'statement', 'builtin',
+    'single', 'pair', 'triple', 'module', 'keyword', 'operator',
+    'object', 'exception', 'statement', 'builtin',
 ]
 
 def index_directive(name, arguments, options, content, lineno,