diff --git a/docs/Manpage.md b/docs/Manpage.md
index 9ca3ac5138..ac3c44ac1a 100644
--- a/docs/Manpage.md
+++ b/docs/Manpage.md
@@ -2144,6 +2144,9 @@ example, run `export HOMEBREW_NO_INSECURE_REDIRECT=1` rather than just
 
   *Default:* macOS: `/private/tmp`, Linux: `/tmp`.
 
+- `HOMEBREW_UPDATE_REPORT_ONLY_INSTALLED`
+  <br>If set, `brew update` only lists updates to installed software.
+
 - `HOMEBREW_UPDATE_TO_TAG`
   <br>If set, always use the latest stable tag (even if developer commands have been run).
 
diff --git a/manpages/brew.1 b/manpages/brew.1
index acc05f5506..6e02dd92f1 100644
--- a/manpages/brew.1
+++ b/manpages/brew.1
@@ -3131,6 +3131,12 @@ Use this path as the temporary directory for building packages\. Changing this m
 \fIDefault:\fR macOS: \fB/private/tmp\fR, Linux: \fB/tmp\fR\.
 .
 .TP
+\fBHOMEBREW_UPDATE_REPORT_ONLY_INSTALLED\fR
+.
+.br
+If set, \fBbrew update\fR only lists updates to installed software\.
+.
+.TP
 \fBHOMEBREW_UPDATE_TO_TAG\fR
 .
 .br