diff --git a/src/config.ts b/src/config.ts
index af98c606..5e2bd58b 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -1,5 +1,3 @@
-'use strict'
-
 import vscode from 'vscode'
 
 export function getSourcegraphUrl(): string {
diff --git a/src/extension.ts b/src/extension.ts
index 244fcb6a..4b07d21a 100644
--- a/src/extension.ts
+++ b/src/extension.ts
@@ -1,5 +1,3 @@
-'use strict'
-
 import opn from 'opn'
 import * as vscode from 'vscode'
 import { getSourcegraphUrl } from './config'
diff --git a/src/git.ts b/src/git.ts
index b16f8376..b4ba86b9 100644
--- a/src/git.ts
+++ b/src/git.ts
@@ -1,5 +1,3 @@
-'use strict'
-
 import execa from 'execa'
 import * as path from 'path'
 
diff --git a/tsconfig.json b/tsconfig.json
index c183e47e..c5ac6ef3 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -7,7 +7,8 @@
     "lib": ["es6"],
     "sourceMap": true,
     "rootDir": "src",
-    "esModuleInterop": true
+    "esModuleInterop": true,
+    "strict": true
   },
   "exclude": ["node_modules", ".vscode-test"]
 }