diff --git a/nandroid.c b/nandroid.c
index ae10ca8..af97e86 100644
--- a/nandroid.c
+++ b/nandroid.c
@@ -101,7 +101,7 @@ typedef void (*file_event_callback)(const char* filename);
 typedef int (*nandroid_backup_handler)(const char* backup_path, const char* backup_file_image, int callback);
 
 static int mkyaffs2image_wrapper(const char* backup_path, const char* backup_file_image, int callback) {
-    return mkyaffs2image(backup_path, backup_file_image, 0, callback);
+    return mkyaffs2image(backup_path, backup_file_image, 0, callback ? yaffs_callback : NULL);
 }
 
 static int tar_compress_wrapper(const char* backup_path, const char* backup_file_image, int callback) {