diff --git a/runtime/doc/diff.txt b/runtime/doc/diff.txt
index 502fb49..d56aea7 100644
--- a/runtime/doc/diff.txt
+++ b/runtime/doc/diff.txt
@@ -384,12 +384,16 @@
 	   endif
 	   silent execute "!diff -a --binary " . opt . v:fname_in . " " . v:fname_new .
 		\  " > " . v:fname_out
+	   redraw!
 	endfunction
 
 The "-a" argument is used to force comparing the files as text, comparing as
 binaries isn't useful.  The "--binary" argument makes the files read in binary
 mode, so that a CTRL-Z doesn't end the text on DOS.
 
+The `redraw!` command may not be needed, depending on whether executing a
+shell command shows something on the display or not.
+
 						*E810* *E97*
 Vim will do a test if the diff output looks alright.  If it doesn't, you will
 get an error message.  Possible causes: