diff --git a/chrony_timex.h b/chrony_timex.h
index e262ff6..287d219 100644
--- a/chrony_timex.h
+++ b/chrony_timex.h
@@ -38,6 +38,7 @@ struct timex {
 #define ADJ_OFFSET		0x0001  /* time offset */
 #define ADJ_FREQUENCY		0x0002	/* frequency offset */
 #define ADJ_MAXERROR		0x0004	/* maximum time error */
+#define ADJ_ESTERROR		0x0008	/* estimated time error */
 #define ADJ_STATUS		0x0010	/* clock status */
 #define ADJ_TIMECONST		0x0020  /* pll time constant */
 #define ADJ_SETOFFSET		0x0100  /* add 'time' to current time */
diff --git a/sys_generic.c b/sys_generic.c
index 3cdb184..44cb251 100644
--- a/sys_generic.c
+++ b/sys_generic.c
@@ -39,9 +39,10 @@
 
 /* ================================================== */
 
-/* System clock frequency drivers */
+/* System clock drivers */
 static lcl_ReadFrequencyDriver drv_read_freq;
 static lcl_SetFrequencyDriver drv_set_freq;
+static lcl_SetSyncStatusDriver drv_set_sync_status;
 
 /* Current frequency as requested by the local module (in ppm) */
 static double base_freq;
@@ -270,6 +271,22 @@ apply_step_offset(double offset)
 
 /* ================================================== */
 
+static void
+set_sync_status(int synchronised, double est_error, double max_error)
+{
+  double offset;
+
+  offset = fabs(offset_register);
+  if (est_error < offset)
+    est_error = offset;
+  max_error += offset;
+
+  if (drv_set_sync_status)
+    drv_set_sync_status(synchronised, est_error, max_error);
+}
+
+/* ================================================== */
+
 void
 SYS_Generic_CompleteFreqDriver(double max_set_freq_ppm, double max_set_freq_delay,
                                lcl_ReadFrequencyDriver sys_read_freq,
@@ -282,6 +299,7 @@ SYS_Generic_CompleteFreqDriver(double max_set_freq_ppm, double max_set_freq_dela
   max_freq_change_delay = max_set_freq_delay * (1.0 + max_freq / 1.0e6);
   drv_read_freq = sys_read_freq;
   drv_set_freq = sys_set_freq;
+  drv_set_sync_status = sys_set_sync_status;
 
   base_freq = (*drv_read_freq)();
   slew_freq = 0.0;
@@ -292,7 +310,7 @@ SYS_Generic_CompleteFreqDriver(double max_set_freq_ppm, double max_set_freq_dela
   lcl_RegisterSystemDrivers(read_frequency, set_frequency,
                             accrue_offset, sys_apply_step_offset ?
                               sys_apply_step_offset : apply_step_offset,
-                            offset_convert, sys_set_leap, NULL);
+                            offset_convert, sys_set_leap, set_sync_status);
 
   LCL_AddParameterChangeHandler(handle_step, NULL);
 }
diff --git a/sys_linux.c b/sys_linux.c
index 4e25751..d03eb2f 100644
--- a/sys_linux.c
+++ b/sys_linux.c
@@ -58,6 +58,9 @@ int LockAll = 0;
 #include "logging.h"
 #include "wrap_adjtimex.h"
 
+/* The threshold for adjtimex maxerror when the kernel sets the UNSYNC flag */
+#define UNSYNC_MAXERROR 16.0
+
 /* This is the uncompensated system tick value */
 static int nominal_tick;
 
@@ -181,6 +184,29 @@ set_leap(int leap)
 
 /* ================================================== */
 
+static void
+set_sync_status(int synchronised, double est_error, double max_error)
+{
+  if (synchronised) {
+    if (est_error > UNSYNC_MAXERROR)
+      est_error = UNSYNC_MAXERROR;
+    if (max_error >= UNSYNC_MAXERROR) {
+      max_error = UNSYNC_MAXERROR;
+      synchronised = 0;
+    }
+  } else {
+    est_error = max_error = UNSYNC_MAXERROR;
+  }
+
+  /* Clear the UNSYNC flag only if rtcsync is enabled */
+  if (!CNF_GetRtcSync())
+    synchronised = 0;
+
+  TMX_SetSync(synchronised, est_error, max_error);
+}
+
+/* ================================================== */
+
 /* Estimate the value of USER_HZ given the value of txc.tick that chronyd finds when
  * it starts.  The only credible values are 100 (Linux/x86) or powers of 2.
  * Also, the bounds checking inside the kernel's adjtimex system call enforces
@@ -334,13 +360,11 @@ SYS_Linux_Initialise(void)
     have_setoffset = 0;
   }
 
-  TMX_SetSync(CNF_GetRtcSync());
-
   SYS_Generic_CompleteFreqDriver(1.0e6 * max_tick_bias / nominal_tick,
                                  1.0 / tick_update_hz,
                                  read_frequency, set_frequency,
                                  have_setoffset ? apply_step_offset : NULL,
-                                 set_leap, NULL);
+                                 set_leap, set_sync_status);
 }
 
 /* ================================================== */
diff --git a/wrap_adjtimex.c b/wrap_adjtimex.c
index 8172c5f..a907ff8 100644
--- a/wrap_adjtimex.c
+++ b/wrap_adjtimex.c
@@ -68,19 +68,11 @@ TMX_SetFrequency(double *freq, long tick)
 {
   struct timex txc;
   
-  txc.modes = ADJ_TICK | ADJ_FREQUENCY | ADJ_STATUS;
+  txc.modes = ADJ_TICK | ADJ_FREQUENCY;
 
   txc.freq = (long)(*freq * (double)(1 << SHIFT_USEC));
   *freq = txc.freq / (double)(1 << SHIFT_USEC);
   txc.tick = tick;
-  txc.status = status; 
-
-  if (!(status & STA_UNSYNC)) {
-    /* maxerror has to be reset periodically to prevent kernel
-       from enabling UNSYNC flag */
-    txc.modes |= ADJ_MAXERROR;
-    txc.maxerror = 0;
-  }
 
   return adjtimex(&txc);
 }
@@ -161,7 +153,7 @@ TMX_SetLeap(int leap)
   return adjtimex(&txc);
 }
 
-int TMX_SetSync(int sync)
+int TMX_SetSync(int sync, double est_error, double max_error)
 {
   struct timex txc;
 
@@ -171,8 +163,10 @@ int TMX_SetSync(int sync)
     status |= STA_UNSYNC;
   }
 
-  txc.modes = ADJ_STATUS;
+  txc.modes = ADJ_STATUS | ADJ_ESTERROR | ADJ_MAXERROR;
   txc.status = status;
+  txc.esterror = est_error * 1.0e6;
+  txc.maxerror = max_error * 1.0e6;
 
   return adjtimex(&txc);
 }
diff --git a/wrap_adjtimex.h b/wrap_adjtimex.h
index e7913b7..4e2bcf4 100644
--- a/wrap_adjtimex.h
+++ b/wrap_adjtimex.h
@@ -69,7 +69,7 @@ int TMX_SetFrequency(double *freq, long tick);
 int TMX_GetFrequency(double *freq, long *tick);
 int TMX_ReadCurrentParams(struct tmx_params *params);
 int TMX_SetLeap(int leap);
-int TMX_SetSync(int sync);
+int TMX_SetSync(int sync, double est_error, double max_error);
 int TMX_TestStepOffset(void);
 int TMX_ApplyStepOffset(double offset);