diff --git a/__tests__/main.test.ts b/__tests__/main.test.ts
index 2593eff..9ac851a 100644
--- a/__tests__/main.test.ts
+++ b/__tests__/main.test.ts
@@ -20,7 +20,7 @@ describe('Integration testing run()', () => {
   test('succeed in installing a custom version', async () => {
     const testVersion: string = '0.61.0';
     process.env['INPUT_HUGO-VERSION'] = testVersion;
-    const result: main.actionResult = await main.run();
+    const result: main.ActionResult = await main.run();
     expect(result.exitcode).toBe(0);
     expect(result.output).toMatch(`Hugo Static Site Generator v${testVersion}`);
   });
@@ -31,14 +31,14 @@ describe('Integration testing run()', () => {
     nock('https://formulae.brew.sh')
       .get(`/api/formula/${repo}.json`)
       .reply(200, jsonTestBrew);
-    const result: main.actionResult = await main.run();
+    const result: main.ActionResult = await main.run();
     expect(result.exitcode).toBe(0);
     expect(result.output).toMatch('Hugo Static Site Generator v0.62.2');
   });
 });
 
 describe('showVersion()', () => {
-  let result: main.actionResult = {
+  let result: main.ActionResult = {
     exitcode: 0,
     output: ''
   };
diff --git a/src/constants.ts b/src/constants.ts
new file mode 100644
index 0000000..e305ca4
--- /dev/null
+++ b/src/constants.ts
@@ -0,0 +1,7 @@
+export enum Tool {
+  Name = 'Hugo',
+  Org = 'gohugoio',
+  Repo = 'hugo',
+  CmdName = 'hugo',
+  CmdOptVersion = 'version'
+}
diff --git a/src/get-latest-version.ts b/src/get-latest-version.ts
index f0031a3..e6f3c37 100644
--- a/src/get-latest-version.ts
+++ b/src/get-latest-version.ts
@@ -1,7 +1,7 @@
 import fetch from 'node-fetch';
 
 export function getURL(org: string, repo: string, api: string): string {
-  let url: string = '';
+  let url = '';
 
   if (api === 'brew') {
     url = `https://formulae.brew.sh/api/formula/${repo}.json`;
@@ -21,7 +21,7 @@ export async function getLatestVersion(
     const url = getURL(org, repo, api);
     const response = await fetch(url);
     const json = await response.json();
-    let latestVersion: string = '';
+    let latestVersion = '';
     if (api === 'brew') {
       latestVersion = json.versions.stable;
     } else if (api === 'github') {
diff --git a/src/get-os.ts b/src/get-os.ts
index b94917a..38a2eba 100644
--- a/src/get-os.ts
+++ b/src/get-os.ts
@@ -1,4 +1,4 @@
-export default function getOS(platform: string) {
+export default function getOS(platform: string): string {
   if (platform === 'linux') {
     return 'Linux';
   } else if (platform === 'darwin') {
diff --git a/src/get-url.ts b/src/get-url.ts
index 42bd9af..ea9726c 100644
--- a/src/get-url.ts
+++ b/src/get-url.ts
@@ -3,7 +3,7 @@ export default function getURL(
   extended: string,
   version: string
 ): string {
-  const extendedStr = (extended: string) => {
+  const extendedStr = (extended: string): string => {
     if (extended === 'true') {
       return 'extended_';
     } else {
@@ -13,7 +13,7 @@ export default function getURL(
     }
   };
 
-  const ext = (os: string) => {
+  const ext = (os: string): string => {
     if (os === 'Windows') {
       return 'zip';
     } else {
@@ -21,11 +21,9 @@ export default function getURL(
     }
   };
 
-  const hugoName: string = `hugo_${extendedStr(
-    extended
-  )}${version}_${os}-64bit`;
-  const baseURL: string = 'https://github.com/gohugoio/hugo/releases/download';
-  const url: string = `${baseURL}/v${version}/${hugoName}.${ext(os)}`;
+  const hugoName = `hugo_${extendedStr(extended)}${version}_${os}-64bit`;
+  const baseURL = 'https://github.com/gohugoio/hugo/releases/download';
+  const url = `${baseURL}/v${version}/${hugoName}.${ext(os)}`;
 
   return url;
 }
diff --git a/src/installer.ts b/src/installer.ts
index 5ce0f37..fb9179e 100644
--- a/src/installer.ts
+++ b/src/installer.ts
@@ -16,7 +16,7 @@ if (!tempDir) {
   tempDir = path.join(baseTempLocation, 'tmp');
 }
 
-export async function installer(version: string) {
+export async function installer(version: string): Promise<void> {
   try {
     const extended: string = core.getInput('extended');
     console.log(`Hugo extended: ${extended}`);
@@ -40,7 +40,7 @@ export async function installer(version: string) {
     // Download and extract Hugo binary
     await io.mkdirP(tempDir);
     const hugoAssets: string = await tc.downloadTool(hugoURL);
-    let hugoBin: string = '';
+    let hugoBin = '';
     if (osName === 'Windows') {
       const hugoExtractedFolder: string = await tc.extractZip(
         hugoAssets,
diff --git a/src/main.ts b/src/main.ts
index 7ebfc21..13b31de 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -2,8 +2,9 @@ import * as core from '@actions/core';
 import * as exec from '@actions/exec';
 import {getLatestVersion} from './get-latest-version';
 import {installer} from './installer';
+import {Tool} from './constants';
 
-export interface actionResult {
+export interface ActionResult {
   exitcode: number;
   output: string;
 }
@@ -11,16 +12,16 @@ export interface actionResult {
 export async function showVersion(
   cmd: string,
   args: string[]
-): Promise<actionResult> {
+): Promise<ActionResult> {
   try {
-    let result: actionResult = {
+    const result: ActionResult = {
       exitcode: 0,
       output: ''
     };
 
     const options = {
       listeners: {
-        stdout: (data: Buffer) => {
+        stdout: (data: Buffer): void => {
           result.output += data.toString();
         }
       }
@@ -37,25 +38,25 @@ export async function showVersion(
   }
 }
 
-export async function run() {
+export async function run(): Promise<ActionResult> {
   try {
     const toolVersion: string = core.getInput('hugo-version');
-    let installVersion: string = '';
+    let installVersion = '';
 
-    let result: actionResult = {
+    let result: ActionResult = {
       exitcode: 0,
       output: ''
     };
 
     if (toolVersion === '' || toolVersion === 'latest') {
-      installVersion = await getLatestVersion('gohugoio', 'hugo', 'brew');
+      installVersion = await getLatestVersion(Tool.Org, Tool.Repo, 'brew');
     } else {
       installVersion = toolVersion;
     }
 
-    core.info(`hugo version: ${installVersion}`);
+    core.info(`${Tool.Name} version: ${installVersion}`);
     await installer(installVersion);
-    result = await showVersion('hugo', ['version']);
+    result = await showVersion(Tool.CmdName, [Tool.CmdOptVersion]);
 
     return result;
   } catch (e) {