diff --git a/tp/Texinfo/XS/parsetexi/end_line.c b/tp/Texinfo/XS/parsetexi/end_line.c
index a5bd0ce..c973cc1 100644
--- a/tp/Texinfo/XS/parsetexi/end_line.c
+++ b/tp/Texinfo/XS/parsetexi/end_line.c
@@ -778,8 +778,8 @@ kdbinputstyle_invalid:
     case CM_headings:
       {
         if (!strcmp (line, "off") || !strcmp (line, "on")
-            || !strcmp (line, "double") || !strcmp (line, "singleafter")
-            || !strcmp (line, "doubleafter"))
+            || !strcmp (line, "single") || !strcmp (line, "double")
+            || !strcmp (line, "singleafter") || !strcmp (line, "doubleafter"))
           {
             ADD_ARG(line);
           }