diff --git a/packages/react-scripts/lib/react-app.d.ts b/packages/react-scripts/lib/react-app.d.ts
index 31e990dedaf..289f975845c 100644
--- a/packages/react-scripts/lib/react-app.d.ts
+++ b/packages/react-scripts/lib/react-app.d.ts
@@ -4,7 +4,6 @@
 
 declare namespace NodeJS {
   interface ProcessEnv {
-    [key: string]: string | undefined
     NODE_ENV: 'development' | 'production' | 'test'
     PUBLIC_URL: string
   }
diff --git a/packages/react-scripts/scripts/utils/verifyTypeScriptSetup.js b/packages/react-scripts/scripts/utils/verifyTypeScriptSetup.js
index 4add778ff49..b1d6a5d71c9 100644
--- a/packages/react-scripts/scripts/utils/verifyTypeScriptSetup.js
+++ b/packages/react-scripts/scripts/utils/verifyTypeScriptSetup.js
@@ -94,7 +94,7 @@ function verifyTypeScriptSetup() {
       suggested: 'es5',
     },
     allowJs: { suggested: true },
-    skipLibCheck: { suggested: true },
+    skipLibCheck: { suggested: false },
     esModuleInterop: { suggested: true },
     allowSyntheticDefaultImports: { suggested: true },
     strict: { suggested: true },