diff --git a/src/_internal/types.ts b/src/_internal/types.ts
index 528dae932..85fc5dde2 100644
--- a/src/_internal/types.ts
+++ b/src/_internal/types.ts
@@ -509,7 +509,10 @@ export type RevalidateCallback = <K extends RevalidateEvent>(
   opts?: any
 ) => RevalidateCallbackReturnType[K]
 
-export interface Cache<Data = any> {
+export type Cache<Data = any> = Omit<
+  Map<any, any>,
+  'keys' | 'get' | 'set' | 'delete'
+> & {
   keys(): IterableIterator<string>
   get(key: string): State<Data> | undefined
   set(key: string, value: State<Data>): void
diff --git a/test/use-swr-cache.test.tsx b/test/use-swr-cache.test.tsx
index 20466383b..fd5fd9646 100644
--- a/test/use-swr-cache.test.tsx
+++ b/test/use-swr-cache.test.tsx
@@ -252,16 +252,24 @@ describe('useSWR - cache provider', () => {
         parentCache = parentCache_
         return {
           keys: () => parentCache.keys(),
-          set: (k, v) => parentCache_.set(k, v),
+          set: (k, v) => parentCache.set(k, v),
           get: k => {
             // We append `-extended` to the value returned by the parent cache.
-            const v = parentCache_.get(k)
+            const v = parentCache.get(k)
             if (v && typeof v.data !== 'undefined') {
               return { ...v, data: v.data + '-extended' }
             }
             return v
           },
-          delete: k => parentCache_.delete(k)
+          delete: k => parentCache.delete(k),
+          clear: () => parentCache.clear(),
+          size: parentCache.size,
+          values: parentCache.values(),
+          has: k => parentCache.has(k),
+          entries: parentCache.entries(),
+          forEach: k => parentCache.forEach(k),
+          [Symbol.iterator]: parentCache[Symbol.iterator](),
+          [Symbol.toStringTag]: parentCache[Symbol.toStringTag]
         }
       }
     })