diff --git a/src/core.ts b/src/core.ts
index 30d77f5..d821ed4 100644
--- a/src/core.ts
+++ b/src/core.ts
@@ -150,15 +150,17 @@ export function setup(
   }
 
   createDebug.namespaces = ''
-  createDebug.names = []
-  createDebug.skips = []
+  createDebug.formatters = {}
   createDebug.enable = enable
   createDebug.disable = disable
   createDebug.enabled = enabled
+
+  // deprecated
+  createDebug.names = []
+  createDebug.skips = []
   createDebug.selectColor = (ns) => selectColor(colors, ns)
   createDebug.formatArgs = formatArgs
   createDebug.log = log
-  createDebug.formatters = {}
 
   createDebug.enable(load())
 
diff --git a/src/types.ts b/src/types.ts
index da54d1c..7b77051 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -16,11 +16,20 @@ export interface Debugger {
   log: (...args: any[]) => any
   extend: (namespace: string, delimiter?: string) => Debugger
 
-  /** @private */
+  /**
+   * @internal
+   * @deprecated It will removed in the next major version. This is internal cache.
+   */
   diff?: number
-  /** @private */
+  /**
+   * @internal
+   * @deprecated It will removed in the next major version. This is internal cache.
+   */
   prev?: number
-  /** @private */
+  /**
+   * @internal
+   * @deprecated It will removed in the next major version. This is internal cache.
+   */
   curr?: number
 }
 
@@ -47,13 +56,30 @@ export interface Debug {
    */
   enabled: (namespaces: string) => boolean
 
+  formatters: Formatters
+  inspectOpts?: InspectOptions
+
+  /**
+   * @deprecated It will removed in the next major version.
+   */
   formatArgs: (this: Debugger, args: [string, ...any[]]) => void
-  log: (...args: any[]) => void
+  /**
+   * @deprecated It will removed in the next major version.
+   */
   selectColor: (namespace: string) => string | number
+  /**
+   * @deprecated It will removed in the next major version.
+   */
+  log: (...args: any[]) => void
 
+  /**
+   * @internal
+   * @deprecated It will removed in the next major version. This is internal cache.
+   */
   names: string[]
+  /**
+   * @internal
+   * @deprecated It will removed in the next major version. This is internal cache.
+   */
   skips: string[]
-
-  formatters: Formatters
-  inspectOpts?: InspectOptions
 }