diff --git a/src/types.ts b/src/types.ts
index 0dea512cd..0f7fad185 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -264,4 +264,5 @@ export interface Cache<Data = any> {
   get(key: Key): Data | null | undefined
   set(key: Key, value: Data): void
   delete(key: Key): void
+  [key: string]: any
 }
diff --git a/test/type/cache.ts b/test/type/cache.ts
new file mode 100644
index 000000000..46292aaa1
--- /dev/null
+++ b/test/type/cache.ts
@@ -0,0 +1,12 @@
+import { useSWRConfig } from 'swr'
+import { expectType } from './utils'
+
+export function useSWRLooseCache() {
+  const { cache } = useSWRConfig()
+  expectType<any>(cache.values())
+}
+
+export function useSWRMapCache() {
+  const cache = useSWRConfig().cache as Map<string, any>
+  expectType<Map<string, any>['values']>(cache.values)
+}