diff --git a/service/src/service/router.ts b/service/src/service/router.ts
index f355c2d..8db70b0 100644
--- a/service/src/service/router.ts
+++ b/service/src/service/router.ts
@@ -365,6 +365,8 @@ router.post('/upload', uploadLimiter, async (req: t.AuthenticatedRequest, res: R
     const bb = busboy({
       headers: req.headers,
       limits: { fileSize: planFileSize },
+      defCharset: 'utf8',
+      defParamCharset: 'utf8',
       preservePath: true,
     });
 
@@ -575,6 +577,8 @@ router.post('/upload/batch', uploadLimiter, async (req: t.AuthenticatedRequest,
     const bb = busboy({
       headers: req.headers,
       limits: { fileSize: planFileSize, files: MAX_BATCH_FILES },
+      defCharset: 'utf8',
+      defParamCharset: 'utf8',
       preservePath: true,
     });