diff --git a/doc/fugitive.txt b/doc/fugitive.txt
index 7d5c10702f..efc59ad2b1 100644
--- a/doc/fugitive.txt
+++ b/doc/fugitive.txt
@@ -357,6 +357,8 @@ Navigation maps ~
                         removed if a count was given.  If the line is still in
                         the work tree version, passing a count takes you to
                         it.
+                        On the 'diff --git' line of a patch, this and similar
+                        maps open a |:Gdiffsplit|.
 
                                                 *fugitive_o*
 o                       Open the file or |fugitive-object| under the cursor in