diff --git a/include/daedalus_v4l2_proto.h b/include/daedalus_v4l2_proto.h
index 04e2dc2..c437e60 100644
--- a/include/daedalus_v4l2_proto.h
+++ b/include/daedalus_v4l2_proto.h
@@ -71,7 +71,18 @@ struct daedalus_msg_hdr {
 	__u32 reserved;
 };
 
-#define DAEDALUS_PROTO_MAX_PAYLOAD	(64u * 1024u)	/* 64 KiB */
+/*
+ * Wire-protocol payload cap.  Sized to comfortably hold real-world
+ * H.264 / VP9 / AV1 access-unit bitstreams:
+ *   - 720p H.264 worst-case I-frame:  ~200 KiB
+ *   - 1080p H.264 worst-case I-frame: ~500 KiB
+ *   - 4K H.264 worst-case I-frame:    ~2 MiB (would need a bump)
+ * 1 MiB is the conservative end of what cedrus / rkvdec / hantro
+ * report as OUTPUT_MPLANE sizeimage.  Allocations (chardev kmalloc
+ * / kmemdup, daemon read buffer, vb2 plane backing) are sized per-
+ * payload at runtime; this only sets the ceiling.  Issue #19.
+ */
+#define DAEDALUS_PROTO_MAX_PAYLOAD	(1024u * 1024u)	/* 1 MiB */
 
 /* -- REQ_DECODE / RESP_FRAME payload structures ---------------------- */