diff --git a/src/installer.ts b/src/installer.ts
index 3897deb..d924eae 100644
--- a/src/installer.ts
+++ b/src/installer.ts
@@ -8,6 +8,7 @@ import fs from 'fs';
 import os from 'os';
 
 type InstallationType = 'dist' | 'manifest';
+export type StableAliasType = 'stable' | 'oldstable';
 
 export interface IGoVersionFile {
   filename: string;
@@ -175,7 +176,7 @@ export async function extractGoArchive(archivePath: string): Promise<string> {
 }
 
 export async function getInfoFromManifest(
-  versionSpec: string,
+  versionSpec: string | StableAliasType,
   stable: boolean,
   auth: string | undefined,
   arch = os.arch()
diff --git a/src/main.ts b/src/main.ts
index 9c2f398..012088f 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -4,7 +4,7 @@ import * as installer from './installer';
 import * as semver from 'semver';
 import path from 'path';
 import {restoreCache} from './cache-restore';
-import {isGhes, isCacheFeatureAvailable} from './cache-utils';
+import {isCacheFeatureAvailable} from './cache-utils';
 import cp from 'child_process';
 import fs from 'fs';
 import os from 'os';
@@ -150,7 +150,7 @@ function resolveVersionInput(): string {
 }
 
 async function resolveStableVersionInput(
-  versionSpec: string,
+  versionSpec: installer.StableAliasType,
   auth: string | undefined,
   arch = os.arch()
 ): Promise<string> {