diff --git a/esm.js b/esm.js
index c045416ca..9231c114b 100644
--- a/esm.js
+++ b/esm.js
@@ -283,6 +283,7 @@ if (cachePath !== "") {
   }
 }
 
+// The legacy symbol used for `esm` export detection.
 defineProperty(makeRequireFunction, shared.symbol.package, {
   __proto__: null,
   value: true
@@ -293,6 +294,11 @@ defineProperty(makeRequireFunction, shared.customInspectKey, {
   value: () => "esm enabled"
 })
 
+defineProperty(makeRequireFunction, "esm:package", {
+  __proto__: null,
+  value: true
+})
+
 defineProperty(makeRequireFunction, "process", {
   __proto__: null,
   value: jestTransform