diff --git a/packages/plugin-legacy/src/index.ts b/packages/plugin-legacy/src/index.ts
index 32d3ba8b0e6c84..dfbda4261519e1 100644
--- a/packages/plugin-legacy/src/index.ts
+++ b/packages/plugin-legacy/src/index.ts
@@ -820,6 +820,7 @@ async function buildPolyfillChunk(
           format,
           hashCharacters: rollupOutputOptions.hashCharacters,
           entryFileNames: rollupOutputOptions.entryFileNames,
+          sourcemapBaseUrl: rollupOutputOptions.sourcemapBaseUrl,
         },
       },
     },