diff --git a/lib/runner_base.js b/lib/runner_base.js
index bafa12e..85e7cc6 100644
--- a/lib/runner_base.js
+++ b/lib/runner_base.js
@@ -84,7 +84,7 @@ class RunnerBase {
         } catch (e) {
           if (e.code !== 'MODULE_NOT_FOUND'       // CommonJS
             && e.code !== 'ERR_MODULE_NOT_FOUND'  // ESM
-            && e.code !== 'ENOENT') {             // ESM w/custom loader
+            && e.code !== 'ENOENT') {             // Testdouble.js, maybe other ESM loaders too
             throw e;
           }
         }