diff --git a/pkgs/by-name/gr/grimorie/package.nix b/pkgs/by-name/gr/grimorie/package.nix
index 5c1dfeb..5e30eae 100644
--- a/pkgs/by-name/gr/grimorie/package.nix
+++ b/pkgs/by-name/gr/grimorie/package.nix
@@ -73,6 +73,12 @@ in
     env.GRIMOIRE_SOCIAL_BASE_URL = "https://grimoire-social.slusheliott.workers.dev";
 
     postPatch = ''
+      # The app is launched via electron directly (not an electron-builder
+      # package), so `app.isPackaged` is false and `is.dev` is true, which
+      # auto-opens DevTools on launch. Strip that call.
+      substituteInPlace electron/main/index.ts \
+        --replace-fail "mainWindow.webContents.openDevTools();" ""
+
       cp -r ${grimoire-social-src} ../grimoire-social
       chmod -R u+w ../grimoire-social