diff --git a/doc/signify.txt b/doc/signify.txt
index 77baa87..95a4633 100644
--- a/doc/signify.txt
+++ b/doc/signify.txt
@@ -159,11 +159,14 @@ Modifiers:~
     %d       |g:signify_difftool|
     %n       Unix: "/dev/null", Windows: "NUL"
 
-NOTE: The output format mustn't change, otherwise Sy won't give any reasonable
+Redirection: Instead of ">foo" use "sy#util#shell_redirect('foo')". This
+helper function takes |'shellredir'| into account.
+
+The output format mustn't change, otherwise Sy won't give any reasonable
 results. It's probably wise to start with the respective default values.
 
-NOTE: If your VCS program is not in $PATH and you have to specify an absolute
-path, escape spaces by quoting, e.g.:
+If your VCS program is not in $PATH and you have to specify an absolute path,
+escape spaces by quoting, e.g.:
 >
     let g:signify_vcs_cmds = {
       \ 'git': '"C:\Program Files (x86)\Git\bin\git.exe" diff --no-color --no-ext-diff -U0 -- %f'
@@ -181,7 +184,7 @@ Default:
       \ 'cvs':      'cvs diff -U0 -- %f',
       \ 'rcs':      'rcsdiff -U0 %f 2>%n',
       \ 'accurev':  'accurev diff %f -- -U0',
-      \ 'perforce': 'p4 info >%n 2>&1 && env P4DIFF=%d p4 diff -dU0 %f',
+      \ 'perforce': 'p4 info '. sy#util#shell_redirect('%n') .' && env P4DIFF=%d p4 diff -dU0 %f'
       \ }
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