diff --git a/src/utilities/common/cloneDeep.ts b/src/utilities/common/cloneDeep.ts
index ddeca7b8067..c4714a3b7e0 100644
--- a/src/utilities/common/cloneDeep.ts
+++ b/src/utilities/common/cloneDeep.ts
@@ -27,12 +27,12 @@ function cloneDeepHelper<T>(val: T, seen?: Map<any, any>): T {
     // possible in all JS environments, so we will assume they exist/work.
     const copy = Object.create(Object.getPrototypeOf(val));
     seen.set(val, copy);
-    Object.keys(val).concat(Object.getOwnPropertySymbols(val) as any).forEach(key => {
+    Object.keys(val).forEach(key => {
       copy[key] = cloneDeepHelper((val as any)[key], seen);
     });
     return copy;
   }
-  
+
   default:
     return val;
   }