diff --git a/src/core/transformer.ts b/src/core/transformer.ts
index 5f94bbfd..f8c5a672 100644
--- a/src/core/transformer.ts
+++ b/src/core/transformer.ts
@@ -32,7 +32,7 @@ export default function transformer(ctx: Context, transformer: SupportedTransfor
 
     const result: TransformResult = { code: s.toString() }
     if (ctx.sourcemap)
-      result.map = s.generateMap({ source: id, includeContent: true })
+      result.map = s.generateMap({ source: id, includeContent: true, hires: 'boundary' })
     return result
   }
 }