diff --git a/docs/Manpage.md b/docs/Manpage.md
index fb1d15e43b..bcdb7dc615 100644
--- a/docs/Manpage.md
+++ b/docs/Manpage.md
@@ -1982,6 +1982,11 @@ example, run `export HOMEBREW_NO_INSECURE_REDIRECT=1` rather than just
 - `HOMEBREW_ADDITIONAL_GOOGLE_ANALYTICS_ID`
   <br>Additional Google Analytics tracking ID to emit user behaviour analytics to. For more information, see: <https://docs.brew.sh/Analytics>
 
+- `HOMEBREW_API_DOMAIN`
+  <br>Use this URL as the download mirror for Homebrew JSON API. If metadata files at that URL are temporarily unavailable, the default API domain will be used as a fallback mirror.
+
+  *Default:* `https://formulae.brew.sh/api`.
+
 - `HOMEBREW_ARCH`
   <br>Linux only: Pass this value to a type name representing the compiler's `-march` option.
 
diff --git a/manpages/brew.1 b/manpages/brew.1
index c6fef33c1d..ede773db01 100644
--- a/manpages/brew.1
+++ b/manpages/brew.1
@@ -2825,6 +2825,15 @@ Note that environment variables must have a value set to be detected\. For examp
 Additional Google Analytics tracking ID to emit user behaviour analytics to\. For more information, see: \fIhttps://docs\.brew\.sh/Analytics\fR
 .
 .TP
+\fBHOMEBREW_API_DOMAIN\fR
+.
+.br
+Use this URL as the download mirror for Homebrew JSON API\. If metadata files at that URL are temporarily unavailable, the default API domain will be used as a fallback mirror\.
+.
+.IP
+\fIDefault:\fR \fBhttps://formulae\.brew\.sh/api\fR\.
+.
+.TP
 \fBHOMEBREW_ARCH\fR
 .
 .br