diff --git a/Style-Guide.md b/Style-Guide.md
index 85e460f..7583d7d 100644
--- a/Style-Guide.md
+++ b/Style-Guide.md
@@ -2,6 +2,7 @@
 ## General
 * Indentation - 2 spaces
 * Line Length - 80 characters
+* [Required License in File Header](https://github.com/mozilla/pdf.js/wiki/License-Headers)
 
 ## Naming
 * variables and functions - lowerCamelCase