diff --git a/runatlantis.io/docs/custom-workflows.md b/runatlantis.io/docs/custom-workflows.md
index 2892df90b7..b92ed0427a 100644
--- a/runatlantis.io/docs/custom-workflows.md
+++ b/runatlantis.io/docs/custom-workflows.md
@@ -318,6 +318,7 @@ Or a custom command
   * `HEAD_REPO_OWNER` - Owner of the repository that is getting merged into the base repository, ex. `acme-corp`.
   * `HEAD_BRANCH_NAME` - Name of the head branch of the pull request (the branch that is getting merged into the base)
   * `BASE_BRANCH_NAME` - Name of the base branch of the pull request (the branch that the pull request is getting merged into)
+  * `PROJECT_NAME` - Name of the project configured in `atlantis.yaml`. If no project name is configured this will be an empty string.
   * `PULL_NUM` - Pull request number or ID, ex. `2`.
   * `PULL_AUTHOR` - Username of the pull request author, ex. `acme-user`.
   * `USER_NAME` - Username of the VCS user running command, ex. `acme-user`. During an autoplan, the user will be the Atlantis API user, ex. `atlantis`.