diff --git a/Userland/Libraries/LibJS/Tests/test-common.js b/Userland/Libraries/LibJS/Tests/test-common.js
index 3c0eec4f11..9141fbe53c 100644
--- a/Userland/Libraries/LibJS/Tests/test-common.js
+++ b/Userland/Libraries/LibJS/Tests/test-common.js
@@ -51,7 +51,14 @@ class ExpectationError extends Error {
         return true;
     };
 
-    const valueToString = value => Object.prototype.toString.call(value);
+    const valueToString = value => {
+        try {
+            return String(value);
+        } catch {
+            // e.g for objects without a prototype, the above throws.
+            return Object.prototype.toString.call(value);
+        }
+    };
 
     class Expector {
         constructor(target, inverted) {