diff --git a/src/plugins/ZeppelinPlugin.ts b/src/plugins/ZeppelinPlugin.ts
index da252d9c..ed71efa4 100644
--- a/src/plugins/ZeppelinPlugin.ts
+++ b/src/plugins/ZeppelinPlugin.ts
@@ -86,7 +86,10 @@ export class ZeppelinPlugin<TConfig extends {} = IBasePluginConfig> extends Plug
       if (decodedOverrideConfig instanceof StrictValidationError) {
         throw decodedOverrideConfig;
       }
-      decodedOverrides.push({ ...override, config: deepKeyIntersect(decodedOverrideConfig, override.config || {}) });
+      decodedOverrides.push({
+        ...override,
+        config: deepKeyIntersect(decodedOverrideConfig, override.config || {}),
+      });
     }
 
     return {
diff --git a/src/utils.ts b/src/utils.ts
index 029e8037..832484b9 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -574,11 +574,19 @@ export class UnknownUser {
   }
 }
 
+export function isObjectLiteral(obj) {
+  let deepestPrototype = obj;
+  while (Object.getPrototypeOf(deepestPrototype) != null) {
+    deepestPrototype = Object.getPrototypeOf(deepestPrototype);
+  }
+  return Object.getPrototypeOf(obj) === deepestPrototype;
+}
+
 export function deepKeyIntersect(obj, keyReference) {
   const result = {};
   for (const [key, value] of Object.entries(obj)) {
     if (!keyReference.hasOwnProperty(key)) continue;
-    if (value != null && typeof value === "object" && typeof keyReference[key] === "object") {
+    if (value != null && typeof value === "object" && typeof keyReference[key] === "object" && isObjectLiteral(value)) {
       result[key] = deepKeyIntersect(value, keyReference[key]);
     } else {
       result[key] = value;