diff --git a/doc/emacs/basic.texi b/doc/emacs/basic.texi
index fc856a3acb7..2e03d0c04a3 100644
--- a/doc/emacs/basic.texi
+++ b/doc/emacs/basic.texi
@@ -467,10 +467,11 @@ changes in the buffer; you can't use it to undo cursor motion.
   On a terminal that supports the @key{Control} modifier on all other
 keys, the easiest way to invoke @code{undo} is with @kbd{C-/}, since
 that doesn't need the @key{Shift} modifier.  On terminals which allow
-only the ASCII control characters, @kbd{C-/} does not exist, but many
-of them allow you to omit the @key{Shift} modifier when you type
-@kbd{C-_} (in effect pressing @kbd{C--}), making that the most
-convenient way to invoke @code{undo}.
+only the ASCII control characters, @kbd{C-/} does not exist, but for
+many of them @kbd{C-/} still works because it actually sends @kbd{C-_}
+to Emacs, while many others allow you to omit the @key{Shift} modifier
+when you type @kbd{C-_} (in effect pressing @kbd{C--}), making that
+the most convenient way to invoke @code{undo}.
 
   Although each editing command usually makes a separate entry in the
 undo records, very simple commands may be grouped together.