diff --git a/packages/react-scripts/lib/react-app.d.ts b/packages/react-scripts/lib/react-app.d.ts
index e384accba5b..8e1752555a7 100644
--- a/packages/react-scripts/lib/react-app.d.ts
+++ b/packages/react-scripts/lib/react-app.d.ts
@@ -4,8 +4,8 @@
 
 declare namespace NodeJS {
   interface ProcessEnv {
-    NODE_ENV: 'development' | 'production' | 'test';
-    PUBLIC_URL: string;
+    readonly NODE_ENV: 'development' | 'production' | 'test';
+    readonly PUBLIC_URL: string;
   }
 }