diff --git a/includes/internal/ping/handlers.h b/includes/internal/ping/handlers.h
new file mode 100644
index 0000000..ba1bc9c
--- /dev/null
+++ b/includes/internal/ping/handlers.h
@@ -0,0 +1,12 @@
+#ifndef PING_HANDLERS_H
+#define PING_HANDLERS_H
+
+#include "icmp.h"
+#include "internal/ping/ping_state.h"
+
+void ping_handle_echo_reply(struct ping_state *state,
+		const icmp_reply_t *reply);
+void ping_handle_icmp_error(struct ping_state *state,
+		const icmp_reply_t *reply);
+
+#endif
diff --git a/includes/internal/ping/output.h b/includes/internal/ping/output.h
index 4c13923..8a49dc7 100644
--- a/includes/internal/ping/output.h
+++ b/includes/internal/ping/output.h
@@ -10,7 +10,8 @@
 void ping_output_start(const struct ping_config *config,
 		struct destinations *dest, size_t payload_bytes);
 void ping_output_packet(const icmp_reply_t *reply, uint16_t seq,
-		int64_t rtt_ns, size_t payload_bytes, const struct ping_config *config);
+		int64_t rtt_ns, size_t payload_bytes, const struct ping_config *config,
+		int is_dup);
 void ping_output_error(const icmp_reply_t *reply,
 		const icmp_offending_packet_t *offending,
 		uint16_t seq, const struct ping_config *config);
diff --git a/includes/internal/ping/ping_state.h b/includes/internal/ping/ping_state.h
index f2725a5..b2c4b57 100644
--- a/includes/internal/ping/ping_state.h
+++ b/includes/internal/ping/ping_state.h
@@ -23,6 +23,7 @@ struct ping_state {
 	volatile sig_atomic_t		send_flag;
 	volatile sig_atomic_t		stop_flag;
 	size_t						nb_errors;
+	int							ts_in_payload;
 };
 
 #endif
diff --git a/includes/internal/ping/tracker.h b/includes/internal/ping/tracker.h
index dd0e49a..be2d82b 100644
--- a/includes/internal/ping/tracker.h
+++ b/includes/internal/ping/tracker.h
@@ -3,28 +3,16 @@
 
 #include <stdint.h>
 #include <stddef.h>
-#include <time.h>
-
-#include "internal/ping/tracker_flags.h"
-
-#define PING_TRACKER_SLOTS	128
-
-struct ping_tracker_slot {
-	struct timespec	ts;
-	uint8_t			flags;
-};
 
 struct ping_tracker {
-	struct ping_tracker_slot	slots[PING_TRACKER_SLOTS];
-	size_t						nb_sent;
-	size_t						nb_recv;
+	uint8_t	rcvd[UINT16_MAX / 8];
+	size_t	nb_sent;
+	size_t	nb_recv;
+	size_t	nb_dup;
 };
 
-void ping_tracker_init(struct ping_tracker *t);
-void ping_tracker_record_send(struct ping_tracker *t, uint16_t seq, const
-		struct timespec *ts);
-int64_t ping_tracker_record_recv(struct ping_tracker *t, uint16_t seq,
-		const struct timespec *ts);
-
+void	ping_tracker_init(struct ping_tracker *t);
+void	ping_tracker_record_send(struct ping_tracker *t, uint16_t seq);
+int		ping_tracker_record_recv(struct ping_tracker *t, uint16_t seq);
 
 #endif
diff --git a/includes/ping/ft_ping_const.h b/includes/ping/ft_ping_const.h
index 9ff04f8..b722d4d 100644
--- a/includes/ping/ft_ping_const.h
+++ b/includes/ping/ft_ping_const.h
@@ -1,6 +1,8 @@
 #ifndef FT_PING_CONST
 #define FT_PING_CONST
 
+#include <time.h>
+
 /* Default configuration values */
 #define DEFAULT_COUNT		0
 #define DEFAULT_PRELOAD		1
@@ -13,4 +15,7 @@
 #define MAX_PACKET_SIZE	65507
 #define MAX_TTL			255
 
+/* Minimum payload size to embed a send timestamp */
+#define PING_TIMESTAMP_SIZE	((size_t)sizeof(struct timespec))
+
 #endif
diff --git a/src/ping/Makefile.am b/src/ping/Makefile.am
index 12f6b1d..6506e55 100644
--- a/src/ping/Makefile.am
+++ b/src/ping/Makefile.am
@@ -69,6 +69,8 @@ libping_core_la_SOURCES		= \
 							  core/loop.c \
 							  core/send.c \
 							  core/callback.c \
+							  core/reply.c \
+							  core/error.c \
 							  tracker/init.c \
 							  tracker/record_send.c \
 							  tracker/record_recv.c \
diff --git a/src/ping/core/callback.c b/src/ping/core/callback.c
index a97c454..1bc67f8 100644
--- a/src/ping/core/callback.c
+++ b/src/ping/core/callback.c
@@ -1,17 +1,5 @@
 #include "icmp_types.h"
-#include "ping/ft_ping_flags.h"
-#include "internal/ping/output.h"
-
-/* Forward declarations */
-static int  extract_our_echo(const icmp_reply_t *reply, uint16_t our_id,
-		struct in_addr dest, uint16_t *seq_out);
-static void handle_echo_reply(struct ping_state *state,
-		const icmp_reply_t *reply);
-static int  extract_our_error(const icmp_reply_t *reply, uint16_t our_id,
-		struct in_addr dest, icmp_offending_packet_t *out, uint16_t *seq_out);
-static void handle_icmp_error(struct ping_state *state,
-		const icmp_reply_t *reply);
-/* -------------------- */
+#include "internal/ping/handlers.h"
 
 void
 ping_callback(const icmp_reply_t *reply, void *userdata)
@@ -20,69 +8,8 @@ ping_callback(const icmp_reply_t *reply, void *userdata)
 
 	state = (struct ping_state *)userdata;
 	if (ICMP_TYPE_ECHO_REPLY == reply->type)
-		handle_echo_reply(state, reply);
+		ping_handle_echo_reply(state, reply);
 	else if (ICMP_TYPE_TIME_EXCEEDED == reply->type
 			|| ICMP_TYPE_DEST_UNREACHABLE == reply->type)
-		handle_icmp_error(state, reply);
-}
-
-static int
-extract_our_echo(const icmp_reply_t *reply, uint16_t our_id,
-		struct in_addr dest, uint16_t *seq_out)
-{
-	uint16_t	id;
-	uint16_t	seq;
-
-	if (0 > icmp_reply_id_seq(reply, &id, &seq))
-		return 0;
-	if (our_id != id || reply->from.s_addr != dest.s_addr)
-		return 0;
-	*seq_out = seq;
-	return 1;
-}
-
-static void
-handle_echo_reply(struct ping_state *state, const icmp_reply_t *reply)
-{
-	uint16_t	seq;
-	int64_t		rtt;
-
-	if (0 == extract_our_echo(reply, state->id, state->dest, &seq))
-		return;
-	rtt = ping_tracker_record_recv(state->tracker, seq, &reply->timestamp);
-	if (0 > rtt)
-		return;
-	ping_stats_update(state->stats, rtt);
-	if (HAS_FLAG(state->config->flags, FLAG_FLOOD))
-		ping_output_flood_erase();
-	else
-		ping_output_packet(reply, seq, rtt, state->config->packet_size,
-				state->config);
-}
-
-static int
-extract_our_error(const icmp_reply_t *reply, uint16_t our_id,
-		struct in_addr dest, icmp_offending_packet_t *out, uint16_t *seq_out)
-{
-	if ((0 > icmp_error_extract_offending(reply, out))
-			|| ICMP_TYPE_ECHO_REQUEST != out->icmp_type
-			|| our_id != out->rest.echo.id || out->dst.s_addr != dest.s_addr)
-		return 0;
-	*seq_out = out->rest.echo.seq;
-	return 1;
-}
-
-static void
-handle_icmp_error(struct ping_state *state, const icmp_reply_t *reply)
-{
-	icmp_offending_packet_t	offending;
-	uint16_t				seq;
-
-	if (0 == extract_our_error(reply, state->id, state->dest, &offending, &seq))
-		return;
-	if (0 > ping_tracker_record_recv(state->tracker, seq, &reply->timestamp))
-		return;
-	state->nb_errors++;
-	if (!HAS_FLAG(state->config->flags, FLAG_QUIET))
-		ping_output_error(reply, &offending, seq, state->config);
+		ping_handle_icmp_error(state, reply);
 }
diff --git a/src/ping/core/error.c b/src/ping/core/error.c
new file mode 100644
index 0000000..b929750
--- /dev/null
+++ b/src/ping/core/error.c
@@ -0,0 +1,37 @@
+#include "icmp.h"
+#include "icmp_types.h"
+#include "ping/ft_ping_flags.h"
+#include "internal/ping/handlers.h"
+#include "internal/ping/output.h"
+
+/* Forward declarations */
+static int extract_our_error(const icmp_reply_t *reply, uint16_t our_id,
+		struct in_addr dest, icmp_offending_packet_t *out, uint16_t *seq_out);
+/* -------------------- */
+
+void
+ping_handle_icmp_error(struct ping_state *state, const icmp_reply_t *reply)
+{
+	icmp_offending_packet_t	offending;
+	uint16_t				seq;
+
+	if (0 == extract_our_error(reply, state->id, state->dest, &offending, &seq))
+		return;
+	if (0 == ping_tracker_record_recv(state->tracker, seq))
+		return;
+	state->nb_errors++;
+	if (!HAS_FLAG(state->config->flags, FLAG_QUIET))
+		ping_output_error(reply, &offending, seq, state->config);
+}
+
+static int
+extract_our_error(const icmp_reply_t *reply, uint16_t our_id,
+		struct in_addr dest, icmp_offending_packet_t *out, uint16_t *seq_out)
+{
+	if ((0 > icmp_error_extract_offending(reply, out))
+			|| ICMP_TYPE_ECHO_REQUEST != out->icmp_type
+			|| our_id != out->rest.echo.id || out->dst.s_addr != dest.s_addr)
+		return 0;
+	*seq_out = out->rest.echo.seq;
+	return 1;
+}
diff --git a/src/ping/core/ping.c b/src/ping/core/ping.c
index 1fbf6a7..9c0d34b 100644
--- a/src/ping/core/ping.c
+++ b/src/ping/core/ping.c
@@ -3,6 +3,7 @@
 #include <stdio.h>
 
 #include "version_gen.h"
+#include "ping/ft_ping_const.h"
 #include "ping/ft_ping_flags.h"
 #include "internal/ping/output.h"
 #include "internal/ping/scheduler.h"
@@ -108,6 +109,7 @@ ping_init_state(struct ping_state *state, struct ping_stats *stats,
 	state->tracker = tracker;
 	state->stats = stats;
 	state->handle = handle;
+	state->ts_in_payload = (config->packet_size >= PING_TIMESTAMP_SIZE);
 	icmp_get_time(&state->start_time);
 }
 
diff --git a/src/ping/core/reply.c b/src/ping/core/reply.c
new file mode 100644
index 0000000..9b2e255
--- /dev/null
+++ b/src/ping/core/reply.c
@@ -0,0 +1,56 @@
+#include <string.h>
+
+#include "icmp.h"
+#include "ping/ft_ping_const.h"
+#include "ping/ft_ping_flags.h"
+#include "internal/ping/handlers.h"
+#include "internal/ping/output.h"
+
+/* Forward declarations */
+static int extract_our_echo(const icmp_reply_t *reply, uint16_t our_id,
+		struct in_addr dest, uint16_t *seq_out);
+/* -------------------- */
+
+void
+ping_handle_echo_reply(struct ping_state *state, const icmp_reply_t *reply)
+{
+	uint16_t		seq;
+	int				is_new;
+	int64_t			rtt_ns;
+	struct timespec	send_ts;
+
+	if (0 == extract_our_echo(reply, state->id, state->dest, &seq))
+		return;
+	is_new = ping_tracker_record_recv(state->tracker, seq);
+	rtt_ns = -1;
+	if (state->ts_in_payload && reply->payload_len >= PING_TIMESTAMP_SIZE)
+	{
+		memcpy(&send_ts, reply->payload, sizeof(send_ts));
+		rtt_ns = icmp_time_diff_ns(&send_ts, &reply->timestamp);
+		if (is_new)
+			ping_stats_update(state->stats, rtt_ns);
+	}
+	if (HAS_FLAG(state->config->flags, FLAG_FLOOD))
+	{
+		if (is_new)
+			ping_output_flood_erase();
+		return;
+	}
+	ping_output_packet(reply, seq, rtt_ns, state->config->packet_size,
+			state->config, !is_new);
+}
+
+static int
+extract_our_echo(const icmp_reply_t *reply, uint16_t our_id,
+		struct in_addr dest, uint16_t *seq_out)
+{
+	uint16_t	id;
+	uint16_t	seq;
+
+	if (0 > icmp_reply_id_seq(reply, &id, &seq))
+		return 0;
+	if (our_id != id || reply->from.s_addr != dest.s_addr)
+		return 0;
+	*seq_out = seq;
+	return 1;
+}
diff --git a/src/ping/core/send.c b/src/ping/core/send.c
index 3aeb7d0..c112d7b 100644
--- a/src/ping/core/send.c
+++ b/src/ping/core/send.c
@@ -12,10 +12,10 @@
 #include "ping/ft_ping_flags.h"
 
 /* Forward declarations */
-static inline void fill_payload(uint8_t *payload, size_t len, const struct
-		ping_config *config);
+static inline void fill_payload(uint8_t *payload, size_t len,
+		const struct ping_config *config, int ts_in_payload);
 static int ping_send_one(struct ping_state *state, uint16_t seq,
-		const uint8_t *payload, size_t payload_len, struct timespec *ts);
+		uint8_t *payload, size_t payload_len, struct timespec *ts);
 /* -------------------- */
 
 void
@@ -26,14 +26,14 @@ do_send(struct ping_state *state, size_t payload_len)
 	int				ret;
 
 	state->send_flag = 0;
-	fill_payload(payload, payload_len, state->config);
+	fill_payload(payload, payload_len, state->config, state->ts_in_payload);
 	ret = ping_send_one(state, state->seq, payload, payload_len, &ts);
 	if (-1 == ret)
 		dprintf(STDERR_FILENO, "%s: %s\n",
 				g_prog_name, icmp_strerror(state->handle));
 	else if (0 == ret)
 	{
-		ping_tracker_record_send(state->tracker, state->seq, &ts);
+		ping_tracker_record_send(state->tracker, state->seq);
 		state->seq++;
 	}
 
@@ -49,12 +49,14 @@ do_send(struct ping_state *state, size_t payload_len)
 
 static int
 ping_send_one(struct ping_state *state, uint16_t seq,
-		const uint8_t *payload, size_t payload_len, struct timespec *ts)
+		uint8_t *payload, size_t payload_len, struct timespec *ts)
 {
 	int ret;
 
 	if (0 != icmp_get_time(ts))
 		return -1;
+	if (state->ts_in_payload)
+		memcpy(payload, ts, sizeof(*ts));
 	ret = icmp_send_echo(state->handle,
 			state->dest,
 			state->id,
@@ -69,16 +71,21 @@ ping_send_one(struct ping_state *state, uint16_t seq,
 }
 
 static inline void
-fill_payload(uint8_t *payload, size_t len, const struct ping_config *config)
+fill_payload(uint8_t *payload, size_t len, const struct ping_config *config,
+		int ts_in_payload)
 {
+	size_t	offset;
+	size_t	i;
+
+	offset = ts_in_payload ? PING_TIMESTAMP_SIZE : 0;
 	if (0 == config->pattern_len)
 	{
-		for (size_t i = 0; i < len; ++i)
-			payload[i] = (uint8_t)('a' + (i % 26));
+		for (i = offset; i < len; ++i)
+			payload[i] = (uint8_t)('a' + ((i - offset) % 26));
 	}
 	else
 	{
-		for (size_t i = 0; i < len; ++i)
-			payload[i] = config->pattern[i % config->pattern_len];
+		for (i = offset; i < len; ++i)
+			payload[i] = config->pattern[(i - offset) % config->pattern_len];
 	}
 }
diff --git a/src/ping/output/packet.c b/src/ping/output/packet.c
index 36568a1..1c7322e 100644
--- a/src/ping/output/packet.c
+++ b/src/ping/output/packet.c
@@ -6,17 +6,27 @@
 
 void
 ping_output_packet(const icmp_reply_t *reply, uint16_t seq,
-		int64_t rtt_ns, size_t payload_bytes, const struct ping_config *config)
+		int64_t rtt_ns, size_t payload_bytes, const struct ping_config *config,
+		int is_dup)
 {
 	char	from_str[INET_ADDRSTRLEN];
 
 	if (HAS_FLAG(config->flags, FLAG_QUIET | FLAG_FLOOD))
 		return;
 	inet_ntop(AF_INET, &reply->from, from_str, sizeof(from_str));
-	printf("%zu bytes from %s: icmp_seq=%u ttl=%u time=%.3f ms\n",
-			payload_bytes + 8,
-			from_str,
-			(unsigned int)seq,
-			(unsigned int)reply->ttl,
-			(double)rtt_ns / 1e6);
+	if (0 <= rtt_ns)
+		printf("%zu bytes from %s: icmp_seq=%u ttl=%u time=%.3f ms%s\n",
+				payload_bytes + 8,
+				from_str,
+				(unsigned int)seq,
+				(unsigned int)reply->ttl,
+				(double)rtt_ns / 1e6,
+				is_dup ? " (DUP!)" : "");
+	else
+		printf("%zu bytes from %s: icmp_seq=%u ttl=%u%s\n",
+				payload_bytes + 8,
+				from_str,
+				(unsigned int)seq,
+				(unsigned int)reply->ttl,
+				is_dup ? " (DUP!)" : "");
 }
diff --git a/src/ping/output/summary.c b/src/ping/output/summary.c
index cac4b87..6161409 100644
--- a/src/ping/output/summary.c
+++ b/src/ping/output/summary.c
@@ -22,7 +22,7 @@ ping_output_summary(const struct ping_state *state,
 	ok_recv = state->tracker->nb_recv - errors;
 	printf("--- %s ping statistics ---\n", dest->dom);
 	print_loss_line(sent, ok_recv, errors);
-	if (0 < ok_recv)
+	if (0 < state->stats->count)
 		print_rtt_line(state->stats);
 }
 
diff --git a/src/ping/tracker/record_recv.c b/src/ping/tracker/record_recv.c
index f8e9974..be6b4a9 100644
--- a/src/ping/tracker/record_recv.c
+++ b/src/ping/tracker/record_recv.c
@@ -1,17 +1,19 @@
-#include "icmp.h"
 #include "internal/ping/tracker.h"
 
-int64_t
-ping_tracker_record_recv(struct ping_tracker *t, uint16_t seq,
-		const struct timespec *ts)
+int
+ping_tracker_record_recv(struct ping_tracker *t, uint16_t seq)
 {
-	struct ping_tracker_slot	*slot;
+	uint8_t	*byte;
+	uint8_t	bit;
 
-	slot = &t->slots[seq % PING_TRACKER_SLOTS];
-	if ((slot->flags & (TRACKER_SLOT_USED | TRACKER_SLOT_ACKED))
-			!= TRACKER_SLOT_USED)
-		return (-1);
-	slot->flags |= TRACKER_SLOT_ACKED;
+	byte = &t->rcvd[seq >> 3];
+	bit  = (uint8_t)(1u << (seq & 7u)); /* 7 == 0b111 */
+	if (*byte & bit)
+	{
+		t->nb_dup++;
+		return (0);
+	}
+	*byte |= bit;
 	t->nb_recv++;
-	return (icmp_time_diff_ns(&slot->ts, ts));
+	return (1);
 }
diff --git a/src/ping/tracker/record_send.c b/src/ping/tracker/record_send.c
index f0ea2d4..33d35cd 100644
--- a/src/ping/tracker/record_send.c
+++ b/src/ping/tracker/record_send.c
@@ -1,13 +1,8 @@
+#include "compiler.h"
 #include "internal/ping/tracker.h"
 
 void
-ping_tracker_record_send(struct ping_tracker *t, uint16_t seq,
-		const struct timespec *ts)
+ping_tracker_record_send(struct ping_tracker *t, uint16_t seq __unused)
 {
-	struct ping_tracker_slot	*slot;
-
-	slot = &t->slots[seq % PING_TRACKER_SLOTS];
-	slot->ts = *ts;
-	slot->flags = TRACKER_SLOT_USED;
 	t->nb_sent++;
 }
diff --git a/tests/ping/tracker/test_tracker.c b/tests/ping/tracker/test_tracker.c
index f205cb7..974e1f3 100644
--- a/tests/ping/tracker/test_tracker.c
+++ b/tests/ping/tracker/test_tracker.c
@@ -2,99 +2,65 @@
 #include <stdint.h>
 #include "internal/ping/tracker.h"
 
-static struct timespec
-make_ts(long sec, long nsec)
-{
-	struct timespec ts;
-
-	ts.tv_sec = sec;
-	ts.tv_nsec = nsec;
-	return (ts);
-}
-
 Test(ping_tracker, init)
 {
-	struct ping_tracker t;
+	struct ping_tracker	t;
 
 	ping_tracker_init(&t);
 	cr_assert_eq(t.nb_sent, (size_t)0);
 	cr_assert_eq(t.nb_recv, (size_t)0);
+	cr_assert_eq(t.nb_dup, (size_t)0);
 }
 
 Test(ping_tracker, basic_send_recv)
 {
 	struct ping_tracker	t;
-	struct timespec	ts_send;
-	struct timespec	ts_recv;
-	int64_t			rtt;
+	int					accepted;
 
 	ping_tracker_init(&t);
-	ts_send = make_ts(1, 0);
-	ts_recv = make_ts(1, 10000000); /* 10 ms later */
-	ping_tracker_record_send(&t, 1, &ts_send);
-	rtt = ping_tracker_record_recv(&t, 1, &ts_recv);
-	cr_assert_eq(rtt, (int64_t)10000000, "Expected RTT of 10ms in ns");
+	ping_tracker_record_send(&t, 1);
+	accepted = ping_tracker_record_recv(&t, 1);
+	cr_assert_eq(accepted, 1);
 	cr_assert_eq(t.nb_sent, (size_t)1);
 	cr_assert_eq(t.nb_recv, (size_t)1);
+	cr_assert_eq(t.nb_dup, (size_t)0);
 }
 
-Test(ping_tracker, double_recv_ignored)
+Test(ping_tracker, double_recv_is_dup)
 {
 	struct ping_tracker	t;
-	struct timespec	ts_send;
-	struct timespec	ts_recv;
-	int64_t			rtt;
+	int					accepted;
 
 	ping_tracker_init(&t);
-	ts_send = make_ts(0, 0);
-	ts_recv = make_ts(0, 5000000);
-	ping_tracker_record_send(&t, 5, &ts_send);
-	rtt = ping_tracker_record_recv(&t, 5, &ts_recv);
-	cr_assert(rtt >= 0, "First recv should succeed");
-	rtt = ping_tracker_record_recv(&t, 5, &ts_recv);
-	cr_assert_eq(rtt, (int64_t)-1, "Duplicate recv should return -1");
+	ping_tracker_record_send(&t, 5);
+	accepted = ping_tracker_record_recv(&t, 5);
+	cr_assert_eq(accepted, 1, "First recv should be accepted");
+	accepted = ping_tracker_record_recv(&t, 5);
+	cr_assert_eq(accepted, 0, "Duplicate recv should return 0");
 	cr_assert_eq(t.nb_recv, (size_t)1);
+	cr_assert_eq(t.nb_dup, (size_t)1);
 }
 
-Test(ping_tracker, unknown_seq_returns_minus_one)
+Test(ping_tracker, unknown_seq_accepted)
 {
 	struct ping_tracker	t;
-	struct timespec	ts;
-	int64_t			rtt;
+	int					accepted;
 
 	ping_tracker_init(&t);
-	ts = make_ts(0, 0);
-	rtt = ping_tracker_record_recv(&t, 42, &ts);
-	cr_assert_eq(rtt, (int64_t)-1);
-}
-
-Test(ping_tracker, wraparound_seq)
-{
-	struct ping_tracker	t;
-	struct timespec	ts_send;
-	struct timespec	ts_recv;
-	int64_t			rtt;
-
-	ping_tracker_init(&t);
-	ts_send = make_ts(0, 0);
-	ts_recv = make_ts(0, 1000000);
-	/* seq 128 maps to slot 0 */
-	ping_tracker_record_send(&t, 128, &ts_send);
-	rtt = ping_tracker_record_recv(&t, 128, &ts_recv);
-	cr_assert_eq(rtt, (int64_t)1000000);
+	accepted = ping_tracker_record_recv(&t, 42);
+	cr_assert_eq(accepted, 1);
+	cr_assert_eq(t.nb_recv, (size_t)1);
 }
 
 Test(ping_tracker, lost_count)
 {
 	struct ping_tracker	t;
-	struct timespec	ts;
 
 	ping_tracker_init(&t);
-	ts = make_ts(0, 0);
-	ping_tracker_record_send(&t, 1, &ts);
-	ping_tracker_record_send(&t, 2, &ts);
-	ping_tracker_record_send(&t, 3, &ts);
-	ping_tracker_record_recv(&t, 2, &ts);
+	ping_tracker_record_send(&t, 1);
+	ping_tracker_record_send(&t, 2);
+	ping_tracker_record_send(&t, 3);
+	ping_tracker_record_recv(&t, 2);
 	cr_assert_eq(t.nb_sent, (size_t)3);
 	cr_assert_eq(t.nb_recv, (size_t)1);
 	cr_assert_eq(t.nb_sent - t.nb_recv, (size_t)2);
@@ -103,63 +69,36 @@ Test(ping_tracker, lost_count)
 Test(ping_tracker, sent_count_increments)
 {
 	struct ping_tracker	t;
-	struct timespec		ts;
 
 	ping_tracker_init(&t);
-	ts = make_ts(0, 0);
-	ping_tracker_record_send(&t, 1, &ts);
-	ping_tracker_record_send(&t, 2, &ts);
-	ping_tracker_record_send(&t, 3, &ts);
+	ping_tracker_record_send(&t, 1);
+	ping_tracker_record_send(&t, 2);
+	ping_tracker_record_send(&t, 3);
 	cr_assert_eq(t.nb_sent, (size_t)3);
 }
 
-Test(ping_tracker, recv_rtt_positive)
+Test(ping_tracker, no_slot_collision_at_256)
 {
 	struct ping_tracker	t;
-	struct timespec		ts_send;
-	struct timespec		ts_recv;
-	int64_t				rtt;
-
-	ping_tracker_init(&t);
-	ts_send = make_ts(1, 0);
-	ts_recv = make_ts(1, 10000000); /* 10 ms later */
-	ping_tracker_record_send(&t, 7, &ts_send);
-	rtt = ping_tracker_record_recv(&t, 7, &ts_recv);
-	cr_assert(rtt > 0, "RTT should be positive");
-}
-
-Test(ping_tracker, slot_reuse_after_wraparound)
-{
-	struct ping_tracker	t;
-	struct timespec		ts_send;
-	struct timespec		ts_recv;
-	int64_t				rtt;
-
-	ping_tracker_init(&t);
-	ts_send = make_ts(0, 0);
-	ts_recv = make_ts(0, 1000000);
-	/* seq=1 -> slot 1 */
-	ping_tracker_record_send(&t, 1, &ts_send);
-	rtt = ping_tracker_record_recv(&t, 1, &ts_recv);
-	cr_assert(rtt >= 0, "First round RTT should be >= 0");
-	/* seq=129 -> slot 129 % 128 = 1, same slot */
-	ping_tracker_record_send(&t, 129, &ts_send);
-	rtt = ping_tracker_record_recv(&t, 129, &ts_recv);
-	cr_assert(rtt >= 0, "Second round RTT should be >= 0");
-	cr_assert_eq(t.nb_sent, (size_t)2);
-	cr_assert_eq(t.nb_recv, (size_t)2);
-}
-
-Test(ping_tracker, full_buffer)
-{
-	struct ping_tracker	t;
-	struct timespec		ts;
 	uint16_t			seq;
 
 	ping_tracker_init(&t);
-	ts = make_ts(0, 0);
-	for (seq = 1; seq <= 128; seq++)
-		ping_tracker_record_send(&t, seq, &ts);
-	cr_assert_eq(t.nb_sent, (size_t)128);
-	cr_assert_eq(t.nb_recv, (size_t)0);
+	for (seq = 0; seq < 256; seq++)
+	{
+		ping_tracker_record_send(&t, seq);
+		cr_assert_eq(ping_tracker_record_recv(&t, seq), 1,
+				"seq %u should be accepted", (unsigned)seq);
+	}
+	cr_assert_eq(t.nb_recv, (size_t)256);
+}
+
+Test(ping_tracker, full_seq_space)
+{
+	struct ping_tracker	t;
+	uint32_t			seq;
+
+	ping_tracker_init(&t);
+	for (seq = 0; seq < 65536; seq++)
+		ping_tracker_record_send(&t, (uint16_t)seq);
+	cr_assert_eq(t.nb_sent, (size_t)65536);
 }
diff --git a/tests/send/test_do_send.c b/tests/send/test_do_send.c
index b9bfa1d..4ddfa8a 100644
--- a/tests/send/test_do_send.c
+++ b/tests/send/test_do_send.c
@@ -9,6 +9,7 @@
 #include "internal/ping/ping_state.h"
 #include "internal/ping/tracker.h"
 #include "ping/ping.h"
+#include "ping/ft_ping_const.h"
 
 /* Controllable mock state */
 int g_mock_send_ret;
@@ -104,3 +105,23 @@ Test(do_send, eagain_then_success_uses_same_seq, .init = setup)
 	cr_assert_eq(g_state.seq, (uint16_t)1);
 	cr_assert_eq(g_tracker.nb_sent, (size_t)1);
 }
+
+Test(do_send, ts_in_payload_increments_seq, .init = setup)
+{
+	g_mock_send_ret      = 0;
+	g_state.ts_in_payload = 1;
+	do_send(&g_state, PING_TIMESTAMP_SIZE);
+	cr_assert_eq(g_state.seq, (uint16_t)1);
+	cr_assert_eq(g_tracker.nb_sent, (size_t)1);
+}
+
+Test(do_send, ts_in_payload_multiple_sends, .init = setup)
+{
+	g_mock_send_ret      = 0;
+	g_state.ts_in_payload = 1;
+	do_send(&g_state, PING_TIMESTAMP_SIZE);
+	do_send(&g_state, PING_TIMESTAMP_SIZE);
+	do_send(&g_state, PING_TIMESTAMP_SIZE);
+	cr_assert_eq(g_state.seq, (uint16_t)3);
+	cr_assert_eq(g_tracker.nb_sent, (size_t)3);
+}