diff --git a/ccid/ccid_device.c b/ccid/ccid_device.c
index c81f177..f10b700 100644
--- a/ccid/ccid_device.c
+++ b/ccid/ccid_device.c
@@ -2,6 +2,7 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <assert.h>
+#include <string.h>
 
 #include <osmocom/core/msgb.h>
 #include <osmocom/core/utils.h>
@@ -19,7 +20,7 @@
 };
 
 struct ccid_ops {
-	int (*send)(struct ccid_instance *ci, struct msgb *msg);
+	int (*send_in)(struct ccid_instance *ci, struct msgb *msg);
 };
 
 struct ccid_instance {
@@ -35,7 +36,7 @@
 	if (slot_nr >= sizeof(ci->slot))
 		return NULL;
 	else
-		return &ci->slot[slot_nr]
+		return &ci->slot[slot_nr];
 }
 
 static uint8_t get_icc_status(const struct ccid_slot *cs)
@@ -67,7 +68,7 @@
 
 static struct msgb *ccid_msgb_alloc(void)
 {
-	struct msgb *msg = msgb_alloc("ccid");
+	struct msgb *msg = msgb_alloc(512, "ccid");
 	OSMO_ASSERT(msg);
 	return msg;
 }
@@ -79,10 +80,10 @@
 
 static int ccid_slot_send(struct ccid_slot *cs, struct msgb *msg)
 {
-	const struct ccid_header *ch = (const struct ccid_header *) msgb_ccid_in(msg);
+	struct ccid_header *ch = (struct ccid_header *) msgb_ccid_in(msg);
 
 	/* patch bSlotNr into message */
-	ch->hdr.bSlot = cs->slot_nr;
+	ch->bSlot = cs->slot_nr;
 	return ccid_send(cs->ci, msg);
 }
 
@@ -93,11 +94,12 @@
 					 uint32_t data_len)
 {
 	struct msgb *msg = ccid_msgb_alloc();
-	struct ccid_rdr_to_pc_data_block *db = msgb_put(msg, sizeof(*db) + data_len);
+	struct ccid_rdr_to_pc_data_block *db = 
+		(struct ccid_rdr_to_pc_data_block *) msgb_put(msg, sizeof(*db) + data_len);
 	uint8_t sts = (cmd_sts & CCID_CMD_STATUS_MASK) | get_icc_status(cs);
 
 	SET_HDR_IN(db, RDR_to_PC_DataBlock, cs->slot_nr, seq, sts, err);
-	db->hdr.dwLength = cpu_to_le32(data_len);
+	osmo_store32le(data_len, &db->hdr.hdr.dwLength);
 	memcpy(db->abData, data, data_len);
 	return msg;
 }
@@ -107,7 +109,8 @@
 					 enum ccid_error_code err)
 {
 	struct msgb *msg = ccid_msgb_alloc();
-	struct ccid_rdr_to_pc_slot_status *ss = msgb_put(msg, sizeof(*ss));
+	struct ccid_rdr_to_pc_slot_status *ss =
+		(struct ccid_rdr_to_pc_slot_status *) msgb_put(msg, sizeof(*ss));
 	uint8_t sts = (cmd_sts & CCID_CMD_STATUS_MASK) | get_icc_status(cs);
 
 	SET_HDR_IN(ss, RDR_to_PC_SlotStatus, cs->slot_nr, seq, sts, err);
@@ -123,11 +126,12 @@
 				    uint32_t data_len)
 {
 	struct msgb *msg = ccid_msgb_alloc();
-	struct ccid_rdr_to_pc_escape *esc = msgb_put(msg, sizeof(*esc) + data_len);
+	struct ccid_rdr_to_pc_escape *esc =
+		(struct ccid_rdr_to_pc_escape *) msgb_put(msg, sizeof(*esc) + data_len);
 	uint8_t sts = (cmd_sts & CCID_CMD_STATUS_MASK) | get_icc_status(cs);
 
 	SET_HDR_IN(esc, RDR_to_PC_Escape, cs->slot_nr, seq, sts, err);
-	esc->hdr.dwLength = cpu_to_le32(data_len);
+	osmo_store32le(data_len, &esc->hdr.hdr.dwLength);
 	memcpy(esc->abData, data, data_len);
 	return msg;
 }
@@ -137,13 +141,14 @@
 					    enum ccid_error_code err, uint32_t clock_khz, uint32_t rate_bps)
 {
 	struct msgb *msg = ccid_msgb_alloc();
-	struct ccid_rdr_to_pc_data_rate_and_clock *drc = msgb_put(msg, sizeof(*drc));
+	struct ccid_rdr_to_pc_data_rate_and_clock *drc =
+		(struct ccid_rdr_to_pc_data_rate_and_clock *) msgb_put(msg, sizeof(*drc));
 	uint8_t sts = (cmd_sts & CCID_CMD_STATUS_MASK) | get_icc_status(cs);
 
 	SET_HDR_IN(drc, RDR_to_PC_DataRateAndClockFrequency, cs->slot_nr, seq, sts, err);
-	drc->dwLength = cpu_to_le32(8); /* Message-specific data length (wtf?) */
-	drc->dwClockFrequency = cpu_to_le32(clock_khz); /* kHz */
-	drc->dwDataRate = cpu_to_le32(rate_bps); /* bps */
+	osmo_store32le(8, &drc->hdr.hdr.dwLength); /* Message-specific data length (wtf?) */
+	osmo_store32le(clock_khz, &drc->dwClockFrequency); /* kHz */
+	osmo_store32le(rate_bps, &drc->dwDataRate); /* bps */
 	return msg;
 }
 
@@ -181,7 +186,7 @@
 
 	/* TODO: send actual ATR; handle error cases */
 	/* TODO: handle this asynchronously */
-	resp = ccid_gen_data_block(cs, u->icc_power_on.hdr.hSeq, CCID_CMD_STATUS_OK, 0, NULL, 0);
+	resp = ccid_gen_data_block(cs, u->icc_power_on.hdr.bSeq, CCID_CMD_STATUS_OK, 0, NULL, 0);
 
 	return ccid_send(cs->ci, resp);
 }
@@ -190,6 +195,8 @@
 static int ccid_handle_icc_power_off(struct ccid_slot *cs, struct msgb *msg)
 {
 	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
+	struct msgb *resp;
+
 	resp = ccid_gen_slot_status(cs, u->get_slot_status.hdr.bSeq, CCID_CMD_STATUS_OK, 0);
 	return ccid_send(cs->ci, resp);
 }
@@ -198,7 +205,9 @@
 static int ccid_handle_xfr_block(struct ccid_slot *cs, struct msgb *msg)
 {
 	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
-	resp = ccid_gen_data_block(cs, u->icc_power_on.hdr.hSeq, CCID_CMD_STATUS_OK, 0, NULL, 0);
+	struct msgb *resp;
+
+	resp = ccid_gen_data_block(cs, u->icc_power_on.hdr.bSeq, CCID_CMD_STATUS_OK, 0, NULL, 0);
 	return ccid_send(cs->ci, resp);
 }
 
@@ -206,30 +215,36 @@
 static int ccid_handle_get_parameters(struct ccid_slot *cs, struct msgb *msg)
 {
 	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
+	struct msgb *resp;
 }
 
 /* Section 6.1.6 */
 static int ccid_handle_reset_parameters(struct ccid_slot *cs, struct msgb *msg)
 {
 	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
+	struct msgb *resp;
 }
 
 /* Section 6.1.7 */
 static int ccid_handle_set_parameters(struct ccid_slot *cs, struct msgb *msg)
 {
 	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
+	struct msgb *resp;
 }
 
 /* Section 6.1.8 */
 static int ccid_handle_escape(struct ccid_slot *cs, struct msgb *msg)
 {
 	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
+	struct msgb *resp;
 }
 
 /* Section 6.1.9 */
 static int ccid_handle_icc_clock(struct ccid_slot *cs, struct msgb *msg)
 {
 	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
+	struct msgb *resp;
+
 	resp = ccid_gen_slot_status(cs, u->get_slot_status.hdr.bSeq, CCID_CMD_STATUS_OK, 0);
 	return ccid_send(cs->ci, resp);
 }
@@ -238,6 +253,8 @@
 static int ccid_handle_t0apdu(struct ccid_slot *cs, struct msgb *msg)
 {
 	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
+	struct msgb *resp;
+
 	resp = ccid_gen_slot_status(cs, u->get_slot_status.hdr.bSeq, CCID_CMD_STATUS_OK, 0);
 	return ccid_send(cs->ci, resp);
 }
@@ -252,6 +269,8 @@
 static int ccid_handle_mechanical(struct ccid_slot *cs, struct msgb *msg)
 {
 	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
+	struct msgb *resp;
+
 	resp = ccid_gen_slot_status(cs, u->get_slot_status.hdr.bSeq, CCID_CMD_STATUS_OK, 0);
 	return ccid_send(cs->ci, resp);
 }
@@ -260,6 +279,8 @@
 static int ccid_handle_abort(struct ccid_slot *cs, struct msgb *msg)
 {
 	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
+	struct msgb *resp;
+
 	resp = ccid_gen_slot_status(cs, u->get_slot_status.hdr.bSeq, CCID_CMD_STATUS_OK, 0);
 	return ccid_send(cs->ci, resp);
 }
@@ -267,7 +288,8 @@
 /* Section 6.1.14 */
 static int ccid_handle_set_rate_and_clock(struct ccid_slot *cs, struct msgb *msg)
 {
-	const union ccid_pc_to_rdr *u = msgb_ccid(msg);
+	const union ccid_pc_to_rdr *u = msgb_ccid_out(msg);
+	struct msgb *resp;
 }
 
 /* handle data arriving from the host on the OUT endpoint */
@@ -277,13 +299,14 @@
 	const struct ccid_header *ch = (const struct ccid_header *) u;
 	unsigned int len = msgb_length(msg);
 	struct ccid_slot *cs;
+	int rc;
 
 	if (len < sizeof(*ch)) {
 		/* FIXME */
 		return -1;
 	}
 
-	cs = get_ccid_slot(ci, ch->hdr.bSlot);
+	cs = get_ccid_slot(ci, ch->bSlot);
 	if (!cs) {
 		/* FIXME */
 		return -1;
@@ -338,7 +361,7 @@
 	case PC_to_RDR_T0APDU:
 		if (len != /*FIXME*/ sizeof(u->t0apdu))
 			goto short_msg;
-		rc = ccid_handle_t0_apdu(cs, msg);
+		rc = ccid_handle_t0apdu(cs, msg);
 		break;
 	case PC_to_RDR_Secure:
 		if (len < sizeof(u->secure))
@@ -361,10 +384,12 @@
 		rc = ccid_handle_set_rate_and_clock(cs, msg);
 		break;
 	default:
-		FIXME
+		/* FIXME */
 		break;
 	}
-	FIXME
+	return 0;
+
 short_msg:
-	FIXME
+	/* FIXME */
+	return -1;
 }