diff --git a/README.md b/README.md
index 2d3b104..86022f5 100644
--- a/README.md
+++ b/README.md
@@ -39,7 +39,7 @@
 1. Clone this repository
 2. Open Thunderbird, go to `Menu > Add-ons and Themes`
 3. Click on the gear icon at the top-right corner and then select "Install Add-on From File..."
-4. Select a theme of choice from `themes` folder of downloaded repository, i.e. `Catppuccin-Mocha-Lavender.zip`
+4. Select a theme of choice from `themes` folder of downloaded repository, i.e. `Catppuccin-Mocha-Lavender.xpi`
 
 ## 💝 Thanks to