diff --git a/mdadm.c b/mdadm.c
index 13dc24e..1b3467f 100644
--- a/mdadm.c
+++ b/mdadm.c
@@ -1433,6 +1433,11 @@ int main(int argc, char *argv[])
 		}
 	}
 
+	if (c.update && strcmp(c.update, "nodes") == 0 && c.nodes == 0) {
+		pr_err("Please specify nodes number with --nodes\n");
+		exit(1);
+	}
+
 	if (c.backup_file && data_offset != INVALID_SECTORS) {
 		pr_err("--backup-file and --data-offset are incompatible\n");
 		exit(2);