diff --git a/packages/store/addon/-private/system/ds-model-store.ts b/packages/store/addon/-private/system/ds-model-store.ts
index d01f05bef1b..41ff62a1da9 100644
--- a/packages/store/addon/-private/system/ds-model-store.ts
+++ b/packages/store/addon/-private/system/ds-model-store.ts
@@ -39,7 +39,7 @@ class Store extends CoreStore {
       _internalModel: internalModel,
       container: null,
     };
-    createOptions = { ...createOptions, ...createRecordArgs };
+    Object.assign(createOptions, createRecordArgs);
 
     // ensure that `getOwner(this)` works inside a model instance
     setOwner(createOptions, getOwner(this));
diff --git a/packages/store/addon/-private/system/model/internal-model.ts b/packages/store/addon/-private/system/model/internal-model.ts
index 71db98bf7e7..d80ae68a625 100644
--- a/packages/store/addon/-private/system/model/internal-model.ts
+++ b/packages/store/addon/-private/system/model/internal-model.ts
@@ -353,7 +353,7 @@ export default class InternalModel {
           }
 
           let additionalCreateOptions = this._recordData._initRecordCreateOptions(properties);
-          createOptions = { ...createOptions, ...additionalCreateOptions };
+          Object.assign(createOptions, additionalCreateOptions);
 
           // ensure that `getOwner(this)` works inside a model instance
           setOwner(createOptions, getOwner(store));
diff --git a/packages/store/addon/-private/system/store/finders.js b/packages/store/addon/-private/system/store/finders.js
index 7a2d9f67dd1..a666ed27090 100644
--- a/packages/store/addon/-private/system/store/finders.js
+++ b/packages/store/addon/-private/system/store/finders.js
@@ -293,7 +293,7 @@ function fixRelationshipData(relationshipData, relationshipKind, { id, modelName
     }
   } else {
     payload = relationshipData || {};
-    payload = { ...payload, ...parentRelationshipData };
+    Object.assign(payload, parentRelationshipData);
   }
 
   return payload;