diff --git a/Ruby.gitignore b/Ruby.gitignore
index e9a8a67c64f4006647264f11f7fb0fb4fa0ae936..5e1422c9c3f1ddaae47b5b1b597bc80748611993 100644
--- a/Ruby.gitignore
+++ b/Ruby.gitignore
@@ -10,6 +10,7 @@
 /test/version_tmp/
 /tmp/
 
+# Used by dotenv library to load environment variables.
 # .env
 
 ## Specific to RubyMotion: