diff --git a/docs/Manpage.md b/docs/Manpage.md
index e411907cab..2bc8aa9343 100644
--- a/docs/Manpage.md
+++ b/docs/Manpage.md
@@ -2005,6 +2005,9 @@ example, run `export HOMEBREW_NO_INSECURE_REDIRECT=1` rather than just
 - `HOMEBREW_NO_INSTALL_CLEANUP`
   <br>If set, `brew install`, `brew upgrade` and `brew reinstall` will never automatically cleanup installed/upgraded/reinstalled formulae or all formulae every `HOMEBREW_CLEANUP_PERIODIC_FULL_DAYS` days.
 
+- `HOMEBREW_NO_INSTALL_UPGRADE`
+  <br>If set, `brew install` will not automatically upgrade installed but outdated formulae
+
 - `HOMEBREW_PRY`
   <br>If set, use Pry for the `brew irb` command.
 
diff --git a/manpages/brew.1 b/manpages/brew.1
index 451355fc9d..bd9d23bb28 100644
--- a/manpages/brew.1
+++ b/manpages/brew.1
@@ -2890,6 +2890,12 @@ If set, forbid redirects from secure HTTPS to insecure HTTP\.
 If set, \fBbrew install\fR, \fBbrew upgrade\fR and \fBbrew reinstall\fR will never automatically cleanup installed/upgraded/reinstalled formulae or all formulae every \fBHOMEBREW_CLEANUP_PERIODIC_FULL_DAYS\fR days\.
 .
 .TP
+\fBHOMEBREW_NO_INSTALL_UPGRADE\fR
+.
+.br
+If set, \fBbrew install\fR will not automatically upgrade installed but outdated formulae
+.
+.TP
 \fBHOMEBREW_PRY\fR
 .
 .br