diff --git a/README.md b/README.md
index 771db7ad..95f4e2a4 100644
--- a/README.md
+++ b/README.md
@@ -581,7 +581,8 @@ syntax:
 
 This works very similar to how we add new syntax definitions.
 > [!NOTE]
-> Themes are stored in [`.tmTheme` files](https://www.sublimetext.com/docs/color_schemes_tmtheme.html).
+> Custom themes must be stored in [`.tmTheme` files](https://www.sublimetext.com/docs/color_schemes_tmtheme.html).
+> Newer `.sublime-color-scheme` files are currently not supported.
 
 First, create a folder with the new syntax highlighting themes:
 ```bash