diff --git a/lib/serializer.js b/lib/serializer.js
index 342c766..ae7229b 100644
--- a/lib/serializer.js
+++ b/lib/serializer.js
@@ -56,7 +56,7 @@ function getFullErrorStack(err) {
 
         out += stackString.shift() + getSerializedContext(e);
         out += stackString.join('\n');
-        e = (e.cause) ? e.cause() : null;
+        e = (typeof e.cause === 'function') ? e.cause() : null;
         first = false;
     } while (e);