diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 671c892..f0dd5a30 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -291,6 +291,8 @@
 			    size_t *retlen, const u_char *buf)
 {
 	*retlen = 0;
+	if (!mtd->write)
+		return -EROFS;
 	return mtd->write(mtd, to, len, retlen, buf);
 }