diff --git a/clientlog.c b/clientlog.c
index 2a18a97..79d643f 100644
--- a/clientlog.c
+++ b/clientlog.c
@@ -38,6 +38,7 @@
 #include "array.h"
 #include "clientlog.h"
 #include "conf.h"
+#include "local.h"
 #include "memory.h"
 #include "ntp.h"
 #include "reports.h"
@@ -125,7 +126,8 @@ static int active;
 /* RX and TX timestamp saved for clients using interleaved mode */
 typedef struct {
   uint64_t rx_ts;
-  uint32_t flags;
+  uint16_t flags;
+  uint16_t slew_epoch;
   int32_t tx_ts_offset;
 } NtpTimestamps;
 
@@ -141,6 +143,8 @@ typedef struct {
   uint32_t max_size;
   uint32_t cached_index;
   uint64_t cached_rx_ts;
+  uint16_t slew_epoch;
+  double slew_offset;
 } NtpTimestampMap;
 
 static NtpTimestampMap ntp_ts_map;
@@ -163,6 +167,8 @@ static uint32_t total_record_drops;
 /* ================================================== */
 
 static int expand_hashtable(void);
+static void handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
+                        double doffset, LCL_ChangeType change_type, void *anything);
 
 /* ================================================== */
 
@@ -407,6 +413,10 @@ CLG_Initialise(void)
   ntp_ts_map.max_size = 1U << (slots2 + SLOT_BITS);
   ntp_ts_map.cached_index = 0;
   ntp_ts_map.cached_rx_ts = 0ULL;
+  ntp_ts_map.slew_epoch = 0;
+  ntp_ts_map.slew_offset = 0.0;
+
+  LCL_AddParameterChangeHandler(handle_slew, NULL);
 }
 
 /* ================================================== */
@@ -420,6 +430,8 @@ CLG_Finalise(void)
   ARR_DestroyInstance(records);
   if (ntp_ts_map.timestamps)
     ARR_DestroyInstance(ntp_ts_map.timestamps);
+
+  LCL_RemoveParameterChangeHandler(handle_slew, NULL);
 }
 
 /* ================================================== */
@@ -864,6 +876,7 @@ CLG_SaveNtpTimestamps(NTP_int64 *rx_ts, struct timespec *tx_ts)
   tss = get_ntp_tss(index);
   tss->rx_ts = rx;
   tss->flags = 0;
+  tss->slew_epoch = ntp_ts_map.slew_epoch;
   set_ntp_tx_offset(tss, rx_ts, tx_ts);
 
   DEBUG_LOG("Saved RX+TX index=%"PRIu32" first=%"PRIu32" size=%"PRIu32,
@@ -872,6 +885,41 @@ CLG_SaveNtpTimestamps(NTP_int64 *rx_ts, struct timespec *tx_ts)
 
 /* ================================================== */
 
+static void
+handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
+            double doffset, LCL_ChangeType change_type, void *anything)
+{
+  /* Drop all timestamps on unknown step */
+  if (change_type == LCL_ChangeUnknownStep) {
+    ntp_ts_map.size = 0;
+    ntp_ts_map.cached_rx_ts = 0ULL;
+  }
+
+  ntp_ts_map.slew_epoch++;
+  ntp_ts_map.slew_offset = doffset;
+}
+
+/* ================================================== */
+
+void
+CLG_UndoNtpTxTimestampSlew(NTP_int64 *rx_ts, struct timespec *tx_ts)
+{
+  uint32_t index;
+
+  if (!ntp_ts_map.timestamps)
+    return;
+
+  if (!find_ntp_rx_ts(ntp64_to_int64(rx_ts), &index))
+    return;
+
+  /* If the RX timestamp was captured before the last correction of the clock,
+     remove the adjustment from the TX timestamp */
+  if ((uint16_t)(get_ntp_tss(index)->slew_epoch + 1U) == ntp_ts_map.slew_epoch)
+    UTI_AddDoubleToTimespec(tx_ts, ntp_ts_map.slew_offset, tx_ts);
+}
+
+/* ================================================== */
+
 void
 CLG_UpdateNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts)
 {
diff --git a/clientlog.h b/clientlog.h
index a400102..2a5565e 100644
--- a/clientlog.h
+++ b/clientlog.h
@@ -47,6 +47,7 @@ extern int CLG_GetNtpMinPoll(void);
 
 /* Functions to save and retrieve timestamps for server interleaved mode */
 extern void CLG_SaveNtpTimestamps(NTP_int64 *rx_ts, struct timespec *tx_ts);
+extern void CLG_UndoNtpTxTimestampSlew(NTP_int64 *rx_ts, struct timespec *tx_ts);
 extern void CLG_UpdateNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts);
 extern int CLG_GetNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts);
 extern void CLG_DisableNtpTimestamps(NTP_int64 *rx_ts);
diff --git a/ntp_core.c b/ntp_core.c
index 40a1f3a..f7c955d 100644
--- a/ntp_core.c
+++ b/ntp_core.c
@@ -2215,7 +2215,7 @@ void
 NCR_ProcessTxUnknown(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr,
                      NTP_Local_Timestamp *tx_ts, NTP_Packet *message, int length)
 {
-  NTP_Local_Timestamp local_tx;
+  NTP_Local_Timestamp old_tx, new_tx;
   NTP_int64 *local_ntp_rx;
   NTP_PacketInfo info;
 
@@ -2229,13 +2229,18 @@ NCR_ProcessTxUnknown(NTP_Remote_Address *remote_addr, NTP_Local_Address *local_a
     UTI_AddDoubleToTimespec(&tx_ts->ts, SMT_GetOffset(&tx_ts->ts), &tx_ts->ts);
 
   local_ntp_rx = &message->receive_ts;
+  new_tx = *tx_ts;
 
-  if (!CLG_GetNtpTxTimestamp(local_ntp_rx, &local_tx.ts))
+  if (!CLG_GetNtpTxTimestamp(local_ntp_rx, &old_tx.ts))
     return;
 
-  update_tx_timestamp(&local_tx, tx_ts, local_ntp_rx, NULL, message);
+  /* Undo a clock adjustment between the RX and TX timestamps to minimise error
+     in the delay measured by the client */
+  CLG_UndoNtpTxTimestampSlew(local_ntp_rx, &new_tx.ts);
 
-  CLG_UpdateNtpTxTimestamp(local_ntp_rx, &local_tx.ts);
+  update_tx_timestamp(&old_tx, &new_tx, local_ntp_rx, NULL, message);
+
+  CLG_UpdateNtpTxTimestamp(local_ntp_rx, &new_tx.ts);
 }
 
 /* ================================================== */
diff --git a/test/unit/clientlog.c b/test/unit/clientlog.c
index b7aed36..2a9a588 100644
--- a/test/unit/clientlog.c
+++ b/test/unit/clientlog.c
@@ -52,6 +52,7 @@ test_unit(void)
   for (i = 0; i < sizeof conf / sizeof conf[0]; i++)
     CNF_ParseLine(NULL, i + 1, conf[i]);
 
+  LCL_Initialise();
   CLG_Initialise();
 
   TEST_CHECK(ARR_GetSize(records) == 16);
@@ -115,6 +116,7 @@ test_unit(void)
     ntp_ts_map.first = i % ntp_ts_map.max_size;
     ntp_ts_map.size = 0;
     ntp_ts_map.cached_rx_ts = 0ULL;
+    ntp_ts_map.slew_epoch = i * 400;
 
     for (j = 0; j < 500; j++) {
       do {
@@ -140,21 +142,41 @@ test_unit(void)
         TEST_CHECK(ntp_ts_map.size == ntp_ts_map.max_size);
         TEST_CHECK(ntp_ts_map.first == (i + j + ntp_ts_map.size + 1) % ntp_ts_map.max_size);
       }
+      TEST_CHECK(ntp_ts_map.cached_index == ntp_ts_map.size - 1);
+      TEST_CHECK(get_ntp_tss(ntp_ts_map.size - 1)->slew_epoch == ntp_ts_map.slew_epoch);
       TEST_CHECK(CLG_GetNtpTxTimestamp(&ntp_ts, &ts2));
       TEST_CHECK(UTI_CompareTimespecs(&ts, &ts2) == 0);
 
       for (k = random() % 4; k > 0; k--) {
-        int64_to_ntp64(get_ntp_tss(random() % ntp_ts_map.size)->rx_ts, &ntp_ts);
+        index2 = random() % ntp_ts_map.size;
+        int64_to_ntp64(get_ntp_tss(index2)->rx_ts, &ntp_ts);
         if (random() % 2)
           TEST_CHECK(CLG_GetNtpTxTimestamp(&ntp_ts, &ts));
 
         UTI_Ntp64ToTimespec(&ntp_ts, &ts);
         UTI_AddDoubleToTimespec(&ts, TST_GetRandomDouble(-1.999, 1.999), &ts);
+
+        ts2 = ts;
+        CLG_UndoNtpTxTimestampSlew(&ntp_ts, &ts);
+        if ((get_ntp_tss(index2)->slew_epoch + 1) % (1U << 16) != ntp_ts_map.slew_epoch) {
+          TEST_CHECK(UTI_CompareTimespecs(&ts, &ts2) == 0);
+        } else {
+          TEST_CHECK(fabs(UTI_DiffTimespecsToDouble(&ts, &ts2) - ntp_ts_map.slew_offset) <
+                     1.0e-9);
+        }
+
         CLG_UpdateNtpTxTimestamp(&ntp_ts, &ts);
 
         TEST_CHECK(CLG_GetNtpTxTimestamp(&ntp_ts, &ts2));
         TEST_CHECK(UTI_CompareTimespecs(&ts, &ts2) == 0);
 
+        if (random() % 2) {
+          uint16_t prev_epoch = ntp_ts_map.slew_epoch;
+          handle_slew(NULL, NULL, 0.0, TST_GetRandomDouble(-1.0e-5, 1.0e-5),
+                      LCL_ChangeAdjust, NULL);
+          TEST_CHECK((prev_epoch + 1) % (1U << 16) == ntp_ts_map.slew_epoch);
+        }
+
         if (ntp_ts_map.size > 1) {
           index = random() % (ntp_ts_map.size - 1);
           if (get_ntp_tss(index)->rx_ts + 1 != get_ntp_tss(index + 1)->rx_ts) {
@@ -163,6 +185,7 @@ test_unit(void)
             int64_to_ntp64(get_ntp_tss(index + 1)->rx_ts - 1, &ntp_ts);
             TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts));
             CLG_UpdateNtpTxTimestamp(&ntp_ts, &ts);
+            CLG_UndoNtpTxTimestampSlew(&ntp_ts, &ts);
           }
         }
 
@@ -172,6 +195,7 @@ test_unit(void)
           int64_to_ntp64(get_ntp_tss(ntp_ts_map.size - 1)->rx_ts + 1, &ntp_ts);
           TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts));
           CLG_UpdateNtpTxTimestamp(&ntp_ts, &ts);
+          CLG_UndoNtpTxTimestampSlew(&ntp_ts, &ts);
         }
       }
     }
@@ -244,9 +268,19 @@ test_unit(void)
         CLG_GetNtpTxTimestamp(&ntp_ts, &ts);
       }
     }
+
+    if (random() % 2) {
+      handle_slew(NULL, NULL, 0.0, TST_GetRandomDouble(-1.0e9, 1.0e9),
+                  LCL_ChangeUnknownStep, NULL);
+      TEST_CHECK(ntp_ts_map.size == 0);
+      TEST_CHECK(ntp_ts_map.cached_rx_ts == 0ULL);
+      TEST_CHECK(!CLG_GetNtpTxTimestamp(&ntp_ts, &ts));
+      CLG_UpdateNtpTxTimestamp(&ntp_ts, &ts);
+    }
   }
 
   CLG_Finalise();
+  LCL_Finalise();
   CNF_Finalise();
 }
 #else