diff --git a/src/axios/cache.ts b/src/axios/cache.ts
index 7c6e790..cdb1f74 100644
--- a/src/axios/cache.ts
+++ b/src/axios/cache.ts
@@ -4,7 +4,7 @@ import { CacheRequestInterceptor } from '../interceptors/request';
 import { CacheResponseInterceptor } from '../interceptors/response';
 import { MemoryStorage } from '../storage/memory';
 import { defaultKeyGenerator } from '../util/key-generator';
-import CacheInstance, { AxiosCacheInstance, CacheProperties } from './types';
+import type { AxiosCacheInstance, CacheInstance, CacheProperties } from './types';
 
 /**
  * Apply the caching interceptors for a already created axios instance.
diff --git a/src/axios/types.ts b/src/axios/types.ts
index 0a89efb..89914b0 100644
--- a/src/axios/types.ts
+++ b/src/axios/types.ts
@@ -6,16 +6,16 @@ import type {
   AxiosResponse,
   Method
 } from 'axios';
-import { HeaderInterpreter } from '../header/types';
-import { AxiosInterceptor } from '../interceptors/types';
-import {
+import type { HeaderInterpreter } from '../header/types';
+import type { AxiosInterceptor } from '../interceptors/types';
+import type {
   CachedResponse,
   CachedStorageValue,
   CacheStorage,
   EmptyStorageValue
 } from '../storage/types';
-import { Deferred } from '../util/deferred';
-import { CachePredicate, KeyGenerator } from '../util/types';
+import type { Deferred } from '../util/deferred';
+import type { CachePredicate, KeyGenerator } from '../util/types';
 
 export type CacheUpdater =
   | 'delete'
@@ -111,7 +111,7 @@ export type CacheRequestConfig = AxiosRequestConfig & {
   cache?: false | Partial<CacheProperties>;
 };
 
-export default interface CacheInstance {
+export interface CacheInstance {
   /**
    * The storage to save the cache data.
    *
diff --git a/src/header/interpreter.ts b/src/header/interpreter.ts
index babf5c7..7747f02 100644
--- a/src/header/interpreter.ts
+++ b/src/header/interpreter.ts
@@ -1,5 +1,5 @@
 import { parse } from '@tusbar/cache-control';
-import { HeaderInterpreter } from './types';
+import type { HeaderInterpreter } from './types';
 
 export const defaultHeaderInterpreter: HeaderInterpreter = (headers) => {
   const cacheControl = headers?.['cache-control'];
diff --git a/src/interceptors/request.ts b/src/interceptors/request.ts
index aa1ebc6..0ee9572 100644
--- a/src/interceptors/request.ts
+++ b/src/interceptors/request.ts
@@ -1,12 +1,12 @@
-import { AxiosCacheInstance, CacheRequestConfig } from '../axios/types';
-import {
+import type { AxiosCacheInstance, CacheRequestConfig } from '../axios/types';
+import type {
   CachedResponse,
   CachedStorageValue,
   LoadingStorageValue
 } from '../storage/types';
 import { deferred } from '../util/deferred';
 import { CACHED_STATUS_CODE, CACHED_STATUS_TEXT } from '../util/status-codes';
-import { AxiosInterceptor } from './types';
+import type { AxiosInterceptor } from './types';
 
 export class CacheRequestInterceptor implements AxiosInterceptor<CacheRequestConfig> {
   constructor(readonly axios: AxiosCacheInstance) {}
diff --git a/src/interceptors/response.ts b/src/interceptors/response.ts
index 73911fd..2186922 100644
--- a/src/interceptors/response.ts
+++ b/src/interceptors/response.ts
@@ -1,14 +1,14 @@
-import { AxiosResponse } from 'axios';
-import {
+import type { AxiosResponse } from 'axios';
+import type {
   AxiosCacheInstance,
   CacheAxiosResponse,
   CacheProperties,
   CacheRequestConfig
 } from '../axios/types';
-import { CachedStorageValue } from '../storage/types';
+import type { CachedStorageValue } from '../storage/types';
 import { checkPredicateObject } from '../util/cache-predicate';
 import { updateCache } from '../util/update-cache';
-import { AxiosInterceptor } from './types';
+import type { AxiosInterceptor } from './types';
 
 type CacheConfig = CacheRequestConfig & { cache?: Partial<CacheProperties> };
 
diff --git a/src/storage/memory.ts b/src/storage/memory.ts
index 659deb9..354fbb7 100644
--- a/src/storage/memory.ts
+++ b/src/storage/memory.ts
@@ -1,4 +1,4 @@
-import { CacheStorage, StorageValue } from './types';
+import type { CacheStorage, StorageValue } from './types';
 
 export class MemoryStorage implements CacheStorage {
   private readonly storage: Map<string, StorageValue> = new Map();
diff --git a/src/storage/web.ts b/src/storage/web.ts
index 97a55a8..6207d39 100644
--- a/src/storage/web.ts
+++ b/src/storage/web.ts
@@ -1,4 +1,4 @@
-import { CacheStorage, StorageValue } from './types';
+import type { CacheStorage, StorageValue } from './types';
 /**
  * A storage that uses any {@link Storage} as his storage.
  */
diff --git a/src/util/cache-predicate.ts b/src/util/cache-predicate.ts
index af6f4a9..4af24bb 100644
--- a/src/util/cache-predicate.ts
+++ b/src/util/cache-predicate.ts
@@ -1,5 +1,5 @@
-import { AxiosResponse } from 'axios';
-import { CachePredicateObject } from './types';
+import type { AxiosResponse } from 'axios';
+import type { CachePredicateObject } from './types';
 
 export function checkPredicateObject(
   response: AxiosResponse,
diff --git a/src/util/key-generator.ts b/src/util/key-generator.ts
index 9a54f83..057bd33 100644
--- a/src/util/key-generator.ts
+++ b/src/util/key-generator.ts
@@ -1,4 +1,4 @@
-import { KeyGenerator } from './types';
+import type { KeyGenerator } from './types';
 
 // Remove first and last '/' char, if present
 // https://regex101.com/r/ENqrFy/1
diff --git a/src/util/types.ts b/src/util/types.ts
index 06b9289..faffc4b 100644
--- a/src/util/types.ts
+++ b/src/util/types.ts
@@ -1,5 +1,5 @@
-import { AxiosResponse } from 'axios';
-import { CacheRequestConfig } from '../axios/types';
+import type { AxiosResponse } from 'axios';
+import type { CacheRequestConfig } from '../axios/types';
 
 export type CachePredicate =
   | CachePredicateObject
diff --git a/src/util/update-cache.ts b/src/util/update-cache.ts
index 9875138..0c2f7fb 100644
--- a/src/util/update-cache.ts
+++ b/src/util/update-cache.ts
@@ -1,4 +1,4 @@
-import { AxiosCacheInstance, CacheUpdater } from '../axios/types';
+import type { AxiosCacheInstance, CacheUpdater } from '../axios/types';
 
 export async function updateCache(
   axios: AxiosCacheInstance,
diff --git a/test/mocks/axios.ts b/test/mocks/axios.ts
index 621ab8e..7e8c556 100644
--- a/test/mocks/axios.ts
+++ b/test/mocks/axios.ts
@@ -1,5 +1,5 @@
 import { AxiosCacheInstance, CacheProperties, createCache } from '../../src';
-import CacheInstance from '../../src/axios/types';
+import type { CacheInstance } from '../../src/axios/types';
 
 export const axiosMock = {
   statusCode: 200,
diff --git a/test/storage/storages.ts b/test/storage/storages.ts
index 23046ac..788cb98 100644
--- a/test/storage/storages.ts
+++ b/test/storage/storages.ts
@@ -1,4 +1,4 @@
-import { CacheStorage } from '../../src/storage/types';
+import type { CacheStorage } from '../../src/storage/types';
 
 export function testStorage(name: string, Storage: () => CacheStorage) {
   it(`tests ${name} storage methods`, async () => {
diff --git a/test/util/cache-predicate.test.ts b/test/util/cache-predicate.test.ts
index 9845500..e78fdaf 100644
--- a/test/util/cache-predicate.test.ts
+++ b/test/util/cache-predicate.test.ts
@@ -1,21 +1,4 @@
-// /**
-//    * The status predicate, if a tuple is returned,
-//    * the first and seconds value means the interval (inclusive) accepted.
-//    * Can also be a function.
-//    */
-//  statusCheck?: [start: number, end: number] | ((status: number) => boolean);
-
-//  /**
-//   * Matches if the response header container all keys. A tuple also checks for values.
-//   */
-//  containsHeaders?: (string | [string, string])[];
-
-//  /**
-//   * Check if the desired response matches this predicate.
-//   */
-//  responseMatch?: <T = any>(res: T | undefined) => boolean;
-
-import { AxiosResponse } from 'axios';
+import type { AxiosResponse } from 'axios';
 import { checkPredicateObject } from '../../src/util/cache-predicate';
 
 const Response = (config: Partial<AxiosResponse>): AxiosResponse => {
diff --git a/test/util/update-cache.test.ts b/test/util/update-cache.test.ts
index e384f54..c550b87 100644
--- a/test/util/update-cache.test.ts
+++ b/test/util/update-cache.test.ts
@@ -1,4 +1,4 @@
-import { AxiosCacheInstance, CachedStorageValue } from '../../src';
+import type { AxiosCacheInstance, CachedStorageValue } from '../../src';
 import { updateCache } from '../../src/util/update-cache';
 import { mockAxios } from '../mocks/axios';
 
diff --git a/tsconfig.json b/tsconfig.json
index d71cf6f..99b92b5 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -51,7 +51,7 @@
     // "removeComments": true,                           /* Disable emitting comments. */
     // "noEmit": true,                                   /* Disable emitting files from a compilation. */
     // "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */
-    // "importsNotUsedAsValues": "remove",               /* Specify emit/checking behavior for imports that are only used for types */
+    "importsNotUsedAsValues": "error",               /* Specify emit/checking behavior for imports that are only used for types */
     "downlevelIteration": true,                       /* Emit more compliant, but verbose and less performant JavaScript for iteration. */
     // "sourceRoot": "",                                 /* Specify the root path for debuggers to find the reference source code. */
     // "mapRoot": "",                                    /* Specify the location where debugger should locate map files instead of generated locations. */