diff --git a/packages/store/addon/-private/system/core-store.ts b/packages/store/addon/-private/system/core-store.ts
index 4e175a6c871..cef4d14939c 100644
--- a/packages/store/addon/-private/system/core-store.ts
+++ b/packages/store/addon/-private/system/core-store.ts
@@ -29,7 +29,6 @@ import { promiseArray, promiseObject } from './promise-proxies';
 import { _bind, _guard, _objectIsAlive, guardDestroyedStore } from './store/common';
 
 import { normalizeResponseHelper } from './store/serializer-response';
-import { serializerForAdapter } from './store/serializers';
 import recordDataFor from './record-data-for';
 import FetchManager, { SaveOp } from './fetch-manager';
 
@@ -3342,14 +3341,14 @@ abstract class CoreStore extends Service {
 
     // no model specific serializer or application serializer, check for the `defaultSerializer`
     // property defined on the adapter
-    if (DEBUG) {
-      deprecate('deprecate adapter.serializer and adapter.defaultSerializer fallbacks', false, {
-        id: 'ember-data:default-serializers',
-        until: '4.0',
-      });
-    }
     let adapter = this.adapterFor(modelName);
     let serializerName = get(adapter, 'defaultSerializer');
+
+    deprecate('deprecate adapter.serializer and adapter.defaultSerializer fallbacks', !serializerName, {
+      id: 'ember-data:default-serializers',
+      until: '4.0',
+    });
+
     serializer = serializerName
       ? _serializerCache[serializerName] || owner.lookup(`serializer:${serializerName}`)
       : undefined;
@@ -3383,12 +3382,6 @@ abstract class CoreStore extends Service {
 
     // final fallback, no model specific serializer, no application serializer, no
     // `serializer` property on store: use json-api serializer
-    if (DEBUG) {
-      deprecate('deprecate -default serializer fallback in store.serializerFor', false, {
-        id: 'ember-data:default-serializers',
-        until: '4.0',
-      });
-    }
     serializer = _serializerCache['-default'] || owner.lookup('serializer:-default');
     if (DEBUG && HAS_SERIALIZER_PACKAGE && serializer === undefined) {
       const JSONSerializer = require('@ember-data/serializer/json').default;
@@ -3398,6 +3391,11 @@ abstract class CoreStore extends Service {
       serializer && deprecateTestRegistration('serializer', '-default');
     }
 
+    deprecate('deprecate -default serializer fallback in store.serializerFor', !serializer, {
+      id: 'ember-data:default-serializers',
+      until: '4.0',
+    });
+
     assert(
       `No serializer was found for '${modelName}' and no 'application' serializer was found as a fallback`,
       serializer !== undefined
@@ -3491,12 +3489,14 @@ defineProperty(
   CoreStore.prototype,
   'defaultAdapter',
   computed('adapter', function() {
-    if (DEBUG) {
-      deprecate('deprecate store.defaultAdapter (-json-api) and the -json-api adapter fallback behavior', false, {
+    deprecate(
+      'deprecate store.adapter, store.defaultAdapter (-json-api) and the -json-api adapter fallback behavior',
+      false,
+      {
         id: 'ember-data:default-adapter',
         until: '4.0',
-      });
-    }
+      }
+    );
     let adapter = this.adapter || '-json-api';
 
     assert(
@@ -3521,7 +3521,7 @@ function _commit(adapter, store, operation, snapshot) {
   );
 
   let promise = Promise.resolve().then(() => adapter[operation](store, modelClass, snapshot));
-  let serializer = serializerForAdapter(store, adapter, modelName);
+  let serializer = store.serializerFor(modelName);
   let label = `DS: Extract and notify about ${operation} completion of ${internalModel}`;
 
   assert(
diff --git a/packages/store/addon/-private/system/fetch-manager.ts b/packages/store/addon/-private/system/fetch-manager.ts
index 4d0e0e559b6..415a5f1f3f4 100644
--- a/packages/store/addon/-private/system/fetch-manager.ts
+++ b/packages/store/addon/-private/system/fetch-manager.ts
@@ -5,7 +5,6 @@ import { assert, warn, inspect } from '@ember/debug';
 import Snapshot from './snapshot';
 import { guardDestroyedStore, _guard, _bind, _objectIsAlive } from './store/common';
 import { normalizeResponseHelper } from './store/serializer-response';
-import { serializerForAdapter } from './store/serializers';
 import { InvalidError } from '@ember-data/adapter/error';
 import coerceId from './coerce-id';
 import { A } from '@ember/array';
@@ -115,7 +114,7 @@ export default class FetchManager {
     );
 
     let promise = Promise.resolve().then(() => adapter[operation](store, modelClass, snapshot));
-    let serializer = serializerForAdapter(store, adapter, modelName);
+    let serializer = store.serializerFor(modelName);
     let label = `DS: Extract and notify about ${operation} completion of ${internalModel}`;
 
     assert(
@@ -262,7 +261,7 @@ export default class FetchManager {
           `You made a 'findRecord' request for a '${modelName}' with id '${id}', but the adapter's response did not have any data`,
           !!payloadIsNotBlank(adapterPayload)
         );
-        let serializer = serializerForAdapter(this._store, adapter, modelName);
+        let serializer = this._store.serializerFor(modelName);
         let payload = normalizeResponseHelper(serializer, this._store, klass, adapterPayload, id, 'findRecord');
         assert(
           `Ember Data expected the primary data returned from a 'findRecord' response to be an object but instead it found an array.`,
@@ -379,7 +378,7 @@ export default class FetchManager {
           `You made a 'findMany' request for '${modelName}' records with ids '[${ids}]', but the adapter's response did not have any data`,
           !!payloadIsNotBlank(adapterPayload)
         );
-        let serializer = serializerForAdapter(store, adapter, modelName);
+        let serializer = store.serializerFor(modelName);
         let payload = normalizeResponseHelper(serializer, store, modelClass, adapterPayload, null, 'findMany');
         return payload;
       },
diff --git a/packages/store/addon/-private/system/model/model.js b/packages/store/addon/-private/system/model/model.js
index 82b630c7762..694ef5761d2 100644
--- a/packages/store/addon/-private/system/model/model.js
+++ b/packages/store/addon/-private/system/model/model.js
@@ -623,12 +623,10 @@ const Model = EmberObject.extend(DeprecatedEvented, {
   */
   toJSON(options) {
     // container is for lazy transform lookups
-    if (DEBUG) {
-      deprecate('deprecate toJSON', false, {
-        id: 'ember-data:model.toJSON',
-        until: '4.0',
-      });
-    }
+    deprecate('deprecate toJSON', false, {
+      id: 'ember-data:model.toJSON',
+      until: '4.0',
+    });
     let serializer = this._internalModel.store.serializerFor('-default');
     let snapshot = this._internalModel.createSnapshot();
 
diff --git a/packages/store/addon/-private/system/store/finders.js b/packages/store/addon/-private/system/store/finders.js
index e617bbff31d..1f887c4b6cf 100644
--- a/packages/store/addon/-private/system/store/finders.js
+++ b/packages/store/addon/-private/system/store/finders.js
@@ -8,7 +8,6 @@ import coerceId from '../coerce-id';
 import { _bind, _guard, _objectIsAlive, guardDestroyedStore } from './common';
 
 import { normalizeResponseHelper } from './serializer-response';
-import { serializerForAdapter } from './serializers';
 import { assign } from '@ember/polyfills';
 import { IDENTIFIERS } from '@ember-data/canary-features';
 import { REQUEST_SERVICE } from '@ember-data/canary-features';
@@ -45,7 +44,7 @@ export function _find(adapter, store, modelClass, id, internalModel, options) {
         `You made a 'findRecord' request for a '${modelName}' with id '${id}', but the adapter's response did not have any data`,
         payloadIsNotBlank(adapterPayload)
       );
-      let serializer = serializerForAdapter(store, adapter, modelName);
+      let serializer = store.serializerFor(modelName);
       let payload = normalizeResponseHelper(serializer, store, modelClass, adapterPayload, id, 'findRecord');
       assert(
         `Ember Data expected the primary data returned from a 'findRecord' response to be an object but instead it found an array.`,
@@ -97,7 +96,7 @@ export function _findMany(adapter, store, modelName, ids, internalModels, option
         `You made a 'findMany' request for '${modelName}' records with ids '[${ids}]', but the adapter's response did not have any data`,
         payloadIsNotBlank(adapterPayload)
       );
-      let serializer = serializerForAdapter(store, adapter, modelName);
+      let serializer = store.serializerFor(modelName);
       let payload = normalizeResponseHelper(serializer, store, modelClass, adapterPayload, null, 'findMany');
       return store._push(payload);
     },
@@ -280,7 +279,7 @@ export function _findHasMany(adapter, store, internalModel, link, relationship,
         `You made a 'findHasMany' request for a ${internalModel.modelName}'s '${relationship.key}' relationship, using link '${link}' , but the adapter's response did not have any data`,
         payloadIsNotBlank(adapterPayload)
       );
-      let serializer = serializerForAdapter(store, adapter, relationship.type);
+      let serializer = store.serializerFor(relationship.type);
       let payload = normalizeResponseHelper(serializer, store, modelClass, adapterPayload, null, 'findHasMany');
 
       syncRelationshipDataFromLink(store, payload, internalModel, relationship);
@@ -305,7 +304,7 @@ export function _findBelongsTo(adapter, store, internalModel, link, relationship
 
   return promise.then(
     adapterPayload => {
-      let serializer = serializerForAdapter(store, adapter, relationship.type);
+      let serializer = store.serializerFor(relationship.type);
       let payload = normalizeResponseHelper(serializer, store, modelClass, adapterPayload, null, 'findBelongsTo');
 
       if (!payload.data) {
@@ -336,7 +335,7 @@ export function _findAll(adapter, store, modelName, options) {
         `You made a 'findAll' request for '${modelName}' records, but the adapter's response did not have any data`,
         payloadIsNotBlank(adapterPayload)
       );
-      let serializer = serializerForAdapter(store, adapter, modelName);
+      let serializer = store.serializerFor(modelName);
       let payload = normalizeResponseHelper(serializer, store, modelClass, adapterPayload, null, 'findAll');
 
       store._push(payload);
@@ -360,7 +359,7 @@ export function _query(adapter, store, modelName, query, recordArray, options) {
 
   return promise.then(
     adapterPayload => {
-      let serializer = serializerForAdapter(store, adapter, modelName);
+      let serializer = store.serializerFor(modelName);
       let payload = normalizeResponseHelper(serializer, store, modelClass, adapterPayload, null, 'query');
       let internalModels = store._push(payload);
 
@@ -395,7 +394,7 @@ export function _queryRecord(adapter, store, modelName, query, options) {
 
   return promise.then(
     adapterPayload => {
-      let serializer = serializerForAdapter(store, adapter, modelName);
+      let serializer = store.serializerFor(modelName);
       let payload = normalizeResponseHelper(serializer, store, modelClass, adapterPayload, null, 'queryRecord');
 
       assert(
diff --git a/packages/store/addon/-private/system/store/serializers.js b/packages/store/addon/-private/system/store/serializers.js
deleted file mode 100644
index d6269870e81..00000000000
--- a/packages/store/addon/-private/system/store/serializers.js
+++ /dev/null
@@ -1,13 +0,0 @@
-/**
-  @module @ember-data/store
-*/
-
-export function serializerForAdapter(store, adapter, modelName) {
-  let serializer = adapter.serializer;
-
-  if (serializer === undefined) {
-    serializer = store.serializerFor(modelName);
-  }
-
-  return serializer;
-}