diff --git a/packages/backend/knexfile.ts b/packages/backend/knexfile.ts
index 440c8ca5..4847933e 100644
--- a/packages/backend/knexfile.ts
+++ b/packages/backend/knexfile.ts
@@ -1,6 +1,6 @@
 import appConfig from './src/config/app';
 
-const fileExtension = appConfig.isDev ? 'ts' : 'js';
+const fileExtension = appConfig.isDev || appConfig.isTest ? 'ts' : 'js';
 
 const knexConfig = {
   client: 'pg',
diff --git a/packages/backend/src/config/app.ts b/packages/backend/src/config/app.ts
index c9354060..01a6982b 100644
--- a/packages/backend/src/config/app.ts
+++ b/packages/backend/src/config/app.ts
@@ -17,6 +17,7 @@ type AppConfig = {
   appEnv: string;
   logLevel: string;
   isDev: boolean;
+  isTest: boolean;
   isProd: boolean;
   postgresDatabase: string;
   postgresSchema: string;
@@ -89,6 +90,7 @@ const appConfig: AppConfig = {
   appEnv: appEnv,
   logLevel: process.env.LOG_LEVEL || 'info',
   isDev: appEnv === 'development',
+  isTest: appEnv === 'test',
   isProd: appEnv === 'production',
   version: process.env.npm_package_version,
   postgresDatabase: process.env.POSTGRES_DATABASE || 'automatisch_development',