diff --git a/pr-checks/update-ghes-versions.ts b/pr-checks/update-ghes-versions.ts
index 784c12a05..283601572 100644
--- a/pr-checks/update-ghes-versions.ts
+++ b/pr-checks/update-ghes-versions.ts
@@ -14,7 +14,19 @@ import { API_COMPATIBILITY_FILE } from "./config";
 /** The first GHES version that included Code Scanning. */
 const FIRST_SUPPORTED_RELEASE: SemVer = new semver.SemVer("2.22.0");
 
-function main() {}
+/** Environment variables specific to this script. */
+export enum EnvVar {
+  ENTERPRISE_RELEASES_PATH = "ENTERPRISE_RELEASES_PATH",
+}
+
+function main() {
+  const enterpriseReleasesPath = process.env[EnvVar.ENTERPRISE_RELEASES_PATH];
+  if (!enterpriseReleasesPath) {
+    throw new Error(
+      `${EnvVar.ENTERPRISE_RELEASES_PATH} environment variable must be set`,
+    );
+  }
+}
 
 // Only call `main` if this script was run directly.
 if (require.main === module) {