diff --git a/packages/next/lib/typescript/diagnosticFormatter.ts b/packages/next/lib/typescript/diagnosticFormatter.ts
index 7b50c9ada0efc27..6d183431415e716 100644
--- a/packages/next/lib/typescript/diagnosticFormatter.ts
+++ b/packages/next/lib/typescript/diagnosticFormatter.ts
@@ -45,7 +45,7 @@ export async function getFormattedDiagnostic(
     const character = pos.character + 1
 
     let fileName = path.posix.normalize(
-      path.relative(baseDir, diagnostic.file.fileName).replace(/\\/, '/')
+      path.relative(baseDir, diagnostic.file.fileName).replace(/\\/g, '/')
     )
     if (!fileName.startsWith('.')) {
       fileName = './' + fileName