diff --git a/server/middleware/upload.js b/server/middleware/upload.js
index ed9f0c7..faa96a5 100644
--- a/server/middleware/upload.js
+++ b/server/middleware/upload.js
@@ -8,6 +8,21 @@ const storage = multer.diskStorage({
     cb(null, config.contentDir);
   },
   filename: (req, file, cb) => {
+    // busboy decodes the Content-Disposition filename header as latin1 by
+    // default. Modern clients send raw UTF-8 bytes for non-ASCII filenames
+    // (e.g. browsers + curl on UTF-8 locales send "Begrussungsscreens.jpg"
+    // with c3 bc for u-umlaut). Reading those bytes as latin1 produces the
+    // string "A-tilde + quarter-mark" which JS then re-encodes as 4 UTF-8
+    // bytes on the way to the DB - classic double-encoding mojibake.
+    //
+    // The `defParamCharset: 'utf8'` option below only takes effect for
+    // RFC 5987 encoded `filename*=...` params, which most clients don't send.
+    // For the plain `filename="..."` case, re-decode here to recover the
+    // original UTF-8 byte sequence. Mutating originalname here propagates to
+    // every downstream consumer (route handlers reading req.file.originalname).
+    if (file.originalname) {
+      file.originalname = Buffer.from(file.originalname, 'latin1').toString('utf8');
+    }
     const ext = path.extname(file.originalname);
     cb(null, `${uuidv4()}${ext}`);
   }