diff --git a/Specification.md b/Specification.md
index 0bc6b4e..e84f247 100644
--- a/Specification.md
+++ b/Specification.md
@@ -1,3 +1,5 @@
+All documentation and comments should be written in English.
+
 ### Configuration
 
 - All options should be put in `conf/app.ini` file in INI format.