diff --git a/src/main.cpp b/src/main.cpp
index cf9c9e5..d09743d 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -150,15 +150,16 @@ void ftpCallback(FtpOperation ftpOperation, uint32_t freeSpace, uint32_t totalSp
  * Called during file transfer operations.
  */
 void ftpTransferCallback(FtpTransferOperation ftpOperation, const char *name, uint32_t transferredSize) {
+    const char *n = (name && name[0]) ? name : "?";
     switch (ftpOperation) {
         case FTP_UPLOAD_START:
-            Serial.printf("[FTP] Upload start: %s\n", name);
+            Serial.printf("[FTP] Upload start: %s\n", n);
             ftp_transfer  = true;
             ftp_ui_state  = FTP_ST_TRANSFERRING;
             ftp_ui_dirty  = true;
             break;
         case FTP_DOWNLOAD_START:
-            Serial.printf("[FTP] Download start: %s\n", name);
+            Serial.printf("[FTP] Download start: %s\n", n);
             ftp_transfer  = true;
             ftp_ui_state  = FTP_ST_TRANSFERRING;
             ftp_ui_dirty  = true;
@@ -167,14 +168,14 @@ void ftpTransferCallback(FtpTransferOperation ftpOperation, const char *name, ui
         case FTP_DOWNLOAD:
             break;  // Ongoing — silent to avoid serial flood
         case FTP_TRANSFER_STOP:
-            Serial.printf("[FTP] Transfer done: %s (%u bytes)\n", name, transferredSize);
+            Serial.printf("[FTP] Transfer done: %s (%lu bytes)\n", n, (unsigned long)transferredSize);
             ftp_transfer  = false;
             ftp_ui_state  = ftp_client_on ? FTP_ST_CONNECTED : FTP_ST_IDLE;
             ftp_ui_dirty  = true;
             ftp_sd_dirty  = true;
             break;
         case FTP_TRANSFER_ERROR:
-            Serial.printf("[FTP] Transfer error: %s\n", name);
+            Serial.printf("[FTP] Transfer error: %s\n", n);
             ftp_transfer  = false;
             ftp_ui_state  = ftp_client_on ? FTP_ST_CONNECTED : FTP_ST_IDLE;
             ftp_ui_dirty  = true;