diff --git a/wire/tlvstream.c b/wire/tlvstream.c
index 6e08981a5..93b91afa9 100644
--- a/wire/tlvstream.c
+++ b/wire/tlvstream.c
@@ -48,7 +48,7 @@ static struct tlv_field *tlvstream_get_raw(struct tlv_field *stream, u64 type)
 	return NULL;
 }
 
-void tlvstream_set_raw(struct tlv_field **stream, u64 type, void *value TAKES, size_t valuelen)
+void tlvstream_set_raw(struct tlv_field **stream, u64 type, const void *value TAKES, size_t valuelen)
 {
 	struct tlv_field f, *e = tlvstream_get_raw(*stream, type);
 
diff --git a/wire/tlvstream.h b/wire/tlvstream.h
index 014d11c55..d9bcfbe48 100644
--- a/wire/tlvstream.h
+++ b/wire/tlvstream.h
@@ -65,7 +65,7 @@ size_t tlv_field_offset(const u8 *tlvstream, size_t tlvlen, u64 fieldtype);
 extern const u64 *FROMWIRE_TLV_ANY_TYPE;
 
 /* Generic primitive setters for tlvstreams. */
-void tlvstream_set_raw(struct tlv_field **stream, u64 type, void *value TAKES, size_t valuelen);
+void tlvstream_set_raw(struct tlv_field **stream, u64 type, const void *value TAKES, size_t valuelen);
 void tlvstream_set_short_channel_id(struct tlv_field **stream, u64 type,
 				    struct short_channel_id *value);
 void tlvstream_set_tu64(struct tlv_field **stream, u64 type, u64 value);