diff --git a/README.md b/README.md
index b3a4cec1..21a9143c 100644
--- a/README.md
+++ b/README.md
@@ -79,6 +79,8 @@ project.
 
 Kotlin code must pass all of [ktlint][ktlint]'s tests.
 
+Always use `//` for single-line comments and `/*` for multi-line comments.
+
 ### Commit messages
 
 Commit messages should follow the ['seven rules'][commitmsg] described in