diff --git a/pkgs/applications/networking/browsers/firefox/packages.nix b/pkgs/applications/networking/browsers/firefox/packages.nix
index a9b631f749c2..e3001d0a08b9 100644
--- a/pkgs/applications/networking/browsers/firefox/packages.nix
+++ b/pkgs/applications/networking/browsers/firefox/packages.nix
@@ -32,10 +32,10 @@ rec {
 
   firefox-esr-78 = common rec {
     pname = "firefox-esr";
-    ffversion = "78.8.0esr";
+    ffversion = "78.9.0esr";
     src = fetchurl {
       url = "mirror://mozilla/firefox/releases/${ffversion}/source/firefox-${ffversion}.source.tar.xz";
-      sha512 = "0160aa6c408c2af66d24b74cf98e1a07ab1604e7b93ffcde79201f9d68e41e896ef965f1904de52d5dd82ffedae33ac96e93b871727bf5dd5983c5af2f1f439f";
+      sha512 = "28582fc0a03fb50c0a817deb1083817bb7f2f5d38e98439bf655ed4ee18c83568b3002a59ef76edf357bfb11f55832a221d14130f116aac19d850768fba3ac8b";
     };
 
     meta = {