diff --git a/pkgs/applications/networking/browsers/firefox/packages/firefox-devedition.nix b/pkgs/applications/networking/browsers/firefox/packages/firefox-devedition.nix
index 50d327a69b93..5b38270109bf 100644
--- a/pkgs/applications/networking/browsers/firefox/packages/firefox-devedition.nix
+++ b/pkgs/applications/networking/browsers/firefox/packages/firefox-devedition.nix
@@ -10,13 +10,13 @@
 buildMozillaMach rec {
   pname = "firefox-devedition";
   binaryName = pname;
-  version = "142.0b8";
+  version = "142.0b9";
   applicationName = "Firefox Developer Edition";
   requireSigning = false;
   branding = "browser/branding/aurora";
   src = fetchurl {
     url = "mirror://mozilla/devedition/releases/${version}/source/firefox-${version}.source.tar.xz";
-    sha512 = "a5a89cdbfe3e05e6d329011476d571625094546e0eb2bea4f4ce426fd8d6ce23ce51ce19fd0a4d44ea7cb134d3f6c1510dcc1403d6aab5981862845a250c9dae";
+    sha512 = "1223065e5c614be9b72f3306daebc98e032d993797bab4d8e646523dfcd9aa554f442b302a32e6281ebb41fcbed49f63097a58fef2a612ae8ff0371f670bad3c";
   };
 
   # buildMozillaMach sets MOZ_APP_REMOTINGNAME during configuration, but