diff --git a/test/internal/appInitializer.js b/test/internal/appInitializer.js
index 3eb9809..d818bc9 100644
--- a/test/internal/appInitializer.js
+++ b/test/internal/appInitializer.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const fastify = require('fastify')
 const { fastifyRequestContextPlugin } = require('../..')
 
diff --git a/test/internal/testService.js b/test/internal/testService.js
index 746e091..f098a8f 100644
--- a/test/internal/testService.js
+++ b/test/internal/testService.js
@@ -1,3 +1,5 @@
+'use strict'
+
 const { requestContext } = require('../..')
 
 // Test class to check if nested calls with promises work correctly with async local storage