diff --git a/.envrc b/.envrc
index 514e4a6..6ab2670 100644
--- a/.envrc
+++ b/.envrc
@@ -13,6 +13,8 @@ branch=$(git branch --show-current)
 if [ $(pwd) == /home/kae/mm ]; then
         export MM_ENV="PRODUCTION"
         export DATABASE_URL="mysql+mysqldb://musicmuster:musicmuster@localhost/musicmuster_prod"
+# on_git_branch is a direnv directive
+# See https://github.com/direnv/direnv/blob/master/man/direnv-stdlib.1.md
 elif on_git_branch master; then
         export MM_ENV="PRODUCTION"
         export DATABASE_URL="mysql+mysqldb://musicmuster:musicmuster@localhost/musicmuster_prod"