diff --git a/doc/assets.md b/doc/assets.md
index 8641188c..a06a1e67 100644
--- a/doc/assets.md
+++ b/doc/assets.md
@@ -16,6 +16,9 @@ in the `.sublime-syntax` format.
 2. If the Sublime Text syntax is only available as a `.tmLanguage` file, open the file in
    Sublime Text and convert it to a `.sublime-syntax` file via *Tools* -> *Developer* ->
    *New Syntax from XXX.tmLanguage...*. Save the new file in the `assets/syntaxes` folder.
+   If only `.tmLanguage.json` or `.tmLanguage.yml` file is available, use
+   [PackageDev](https://packagecontrol.io/packages/PackageDev) to convert it to `.tmLanguage.plist`
+   format and then rename the converted file to `.tmLanguage` file.
 
 3. Run the `assets/create.sh` script. It calls `bat cache --build` to parse all available
    `.sublime-syntax` files and serialize them to a `syntaxes.bin` file.