diff --git a/spi25.c b/spi25.c
index 734df28..b13318b 100644
--- a/spi25.c
+++ b/spi25.c
@@ -441,6 +441,8 @@
 		msg_cerr("%s called for too long a write\n", __func__);
 		return 1;
 	}
+	if (!out_bytes && out_len > 0)
+		return 1;
 
 	memcpy(cmd + 1 + addr_len, out_bytes, out_len);
 	cmds[1].writecnt = 1 + addr_len + out_len;