diff --git a/pkgs/applications/networking/browsers/firefox/packages.nix b/pkgs/applications/networking/browsers/firefox/packages.nix
index e591324c2cc8..34fe4a6fddfd 100644
--- a/pkgs/applications/networking/browsers/firefox/packages.nix
+++ b/pkgs/applications/networking/browsers/firefox/packages.nix
@@ -55,11 +55,11 @@ rec {
 
   firefox-esr-91 = buildMozillaMach rec {
     pname = "firefox-esr";
-    version = "91.11.0esr";
+    version = "91.12.0esr";
     applicationName = "Mozilla Firefox ESR";
     src = fetchurl {
       url = "mirror://mozilla/firefox/releases/${version}/source/firefox-${version}.source.tar.xz";
-      sha512 = "bff3a399c03bd1cdaaec0b6963b1558aa35b6338b6c02042ffd65fec0aedd344d01718692e881332f5f352c32da15ba09a20a09ee072200b47ae840bc0585a96";
+      sha512 = "323fb752488b45872b40f0b0ee1d8c1dffa16874dbff2afde19a54286c824ef48177233e029faeafa5946184e71c31c6bc5ba7ec17a571e21af64fc5f7334042";
     };
 
     meta = {