diff --git a/doc/api/esm.md b/doc/api/esm.md
index 34791f89e0c845..476d076deb3239 100644
--- a/doc/api/esm.md
+++ b/doc/api/esm.md
@@ -376,6 +376,9 @@ behind the `--experimental-import-meta-resolve` flag:
 
 * `parent` {string|URL} An optional absolute parent module URL to resolve from.
 
+> **Caveat** This feature is not available within custom loaders (it would
+> create a deadlock).
+
 ## Interoperability with CommonJS
 
 ### `import` statements