diff --git a/src/runtime/browser/util.inspect.polyfil.ts b/src/runtime/browser/util.inspect.polyfil.ts
index 9f15b1f..f953176 100644
--- a/src/runtime/browser/util.inspect.polyfil.ts
+++ b/src/runtime/browser/util.inspect.polyfil.ts
@@ -377,19 +377,18 @@ function reduceToSingleString(output: string[], base: string, braces: string[]):
   return braces[0] + (base === "" ? "" : base + "\n") + "  " + output.join(",\n  ") + " " + braces[1];
 }
 
-function _extend(origin: object, add: object): object {
-  const typedOrigin = { ...origin } as { [key: string]: unknown };
+function _extend(origin: object, add: object): void {
+  const typedOrigin = origin as {[key: string]: unknown};
   // Don't do anything if add isn't an object
-  if (!add || !isObject(add)) return origin;
+  if (!add || !isObject(add)) return;
 
-  const clonedAdd = { ...add } as { [key: string]: unknown };
+  const clonedAdd = {...add} as {[key: string]: unknown};
 
   const keys = Object.keys(add);
   let i = keys.length;
   while (i--) {
     typedOrigin[keys[i]] = clonedAdd[keys[i]];
   }
-  return typedOrigin;
 }
 
 export function formatWithOptions(inspectOptions: InspectOptions, ...args: unknown[]) {