diff --git a/sys/fs/msdosfs/msdosfs_conv.c b/sys/fs/msdosfs/msdosfs_conv.c
index efd219135a1e..8c2d5f40fe54 100644
--- a/sys/fs/msdosfs/msdosfs_conv.c
+++ b/sys/fs/msdosfs/msdosfs_conv.c
@@ -1249,8 +1249,8 @@ mbnambuf_flush(struct dirent *dp)
 		mbnambuf_init();
 		return (NULL);
 	}
-	nambuf_ptr[nambuf_len] = '\0';
 	memcpy(dp->d_name, nambuf_ptr, nambuf_len);
+	dp->d_name[nambuf_len] = '\0';
 	dp->d_namlen = nambuf_len;
 
 	mbnambuf_init();