diff --git a/refclock.c b/refclock.c
index 1a99f53..cd09ebc 100644
--- a/refclock.c
+++ b/refclock.c
@@ -91,6 +91,7 @@ static int pps_stratum(RCL_Instance instance, struct timeval *tv);
 static void poll_timeout(void *arg);
 static void slew_samples(struct timeval *raw, struct timeval *cooked, double dfreq, double afreq,
              double doffset, int is_step_change, void *anything);
+static void add_dispersion(double dispersion, void *anything);
 static void log_sample(RCL_Instance instance, struct timeval *sample_time, int pulse, double raw_offset, double cooked_offset, double dispersion);
 
 static void filter_init(struct MedianFilter *filter, int length);
@@ -100,6 +101,7 @@ static void filter_add_sample(struct MedianFilter *filter, struct timeval *sampl
 static int filter_get_last_sample(struct MedianFilter *filter, struct timeval *sample_time, double *offset, double *dispersion);
 static int filter_get_sample(struct MedianFilter *filter, struct timeval *sample_time, double *offset, double *dispersion);
 static void filter_slew_samples(struct MedianFilter *filter, struct timeval *when, double dfreq, double doffset);
+static void filter_add_dispersion(struct MedianFilter *filter, double dispersion);
 
 void
 RCL_Initialise(void)
@@ -134,8 +136,10 @@ RCL_Finalise(void)
     Free(inst->driver_parameter);
   }
 
-  if (n_sources > 0)
+  if (n_sources > 0) {
     LCL_RemoveParameterChangeHandler(slew_samples, NULL);
+    LCL_RemoveDispersionNotifyHandler(add_dispersion, NULL);
+  }
 
   if (logfile)
     fclose(logfile);
@@ -250,8 +254,10 @@ RCL_StartRefclocks(void)
       inst->lock_ref = -1;
   }
 
-  if (n_sources > 0)
+  if (n_sources > 0) {
     LCL_AddParameterChangeHandler(slew_samples, NULL);
+    LCL_AddDispersionNotifyHandler(add_dispersion, NULL);
+  }
 }
 
 void
@@ -548,6 +554,15 @@ slew_samples(struct timeval *raw, struct timeval *cooked, double dfreq, double a
     filter_slew_samples(&refclocks[i].filter, cooked, dfreq, doffset);
 }
 
+static void
+add_dispersion(double dispersion, void *anything)
+{
+  int i;
+
+  for (i = 0; i < n_sources; i++)
+    filter_add_dispersion(&refclocks[i].filter, dispersion);
+}
+
 static void
 log_sample(RCL_Instance instance, struct timeval *sample_time, int pulse, double raw_offset, double cooked_offset, double dispersion)
 {
@@ -752,3 +767,13 @@ filter_slew_samples(struct MedianFilter *filter, struct timeval *when, double df
 #endif
   }
 }
+
+static void
+filter_add_dispersion(struct MedianFilter *filter, double dispersion)
+{
+  int i;
+
+  for (i = 0; i < filter->used; i++) {
+    filter->samples[i].dispersion += dispersion;
+  }
+}
diff --git a/sources.c b/sources.c
index f27583b..f1674f2 100644
--- a/sources.c
+++ b/sources.c
@@ -130,6 +130,8 @@ static int selected_source_index; /* Which source index is currently
 static void
 slew_sources(struct timeval *raw, struct timeval *cooked, double dfreq, double afreq,
              double doffset, int is_step_change, void *anything);
+static void
+add_dispersion(double dispersion, void *anything);
 static char *
 source_to_string(SRC_Instance inst);
 
@@ -144,6 +146,7 @@ void SRC_Initialise(void) {
   initialised = 1;
 
   LCL_AddParameterChangeHandler(slew_sources, NULL);
+  LCL_AddDispersionNotifyHandler(add_dispersion, NULL);
 
   return;
 }
@@ -153,6 +156,7 @@ void SRC_Initialise(void) {
 void SRC_Finalise(void)
 {
   LCL_RemoveParameterChangeHandler(slew_sources, NULL);
+  LCL_RemoveDispersionNotifyHandler(add_dispersion, NULL);
   initialised = 0;
   return;
 }
@@ -807,6 +811,20 @@ slew_sources(struct timeval *raw,
   
 }
 
+/* ================================================== */
+/* This routine is called when an indeterminate offset is introduced
+   into the local time. */
+
+static void
+add_dispersion(double dispersion, void *anything)
+{
+  int i;
+
+  for (i = 0; i < n_sources; i++) {
+    SST_AddDispersion(sources[i]->stats, dispersion);
+  }
+}
+
 /* ================================================== */
 /* This is called to dump out the source measurement registers */
 
diff --git a/sourcestats.c b/sourcestats.c
index 3dc61e0..2ecae89 100644
--- a/sourcestats.c
+++ b/sourcestats.c
@@ -717,6 +717,19 @@ SST_SlewSamples(SST_Stats inst, struct timeval *when, double dfreq, double doffs
 
 /* ================================================== */
 
+void 
+SST_AddDispersion(SST_Stats inst, double dispersion)
+{
+  int i;
+
+  for (i=0; i < inst->n_samples; i++) {
+    inst->root_dispersions[i] += dispersion;
+    inst->peer_dispersions[i] += dispersion;
+  }
+}
+
+/* ================================================== */
+
 double
 SST_PredictOffset(SST_Stats inst, struct timeval *when)
 {
diff --git a/sourcestats.h b/sourcestats.h
index 0a5a82b..5e787d8 100644
--- a/sourcestats.h
+++ b/sourcestats.h
@@ -125,6 +125,9 @@ SST_GetReferenceData(SST_Stats inst, struct timeval *now,
 
 extern void SST_SlewSamples(SST_Stats inst, struct timeval *when, double dfreq, double doffset);
 
+/* This routine is called when an indeterminate offset is introduced
+   into the local time. */
+extern void SST_AddDispersion(SST_Stats inst, double dispersion);
 
 /* Predict the offset of the local clock relative to a given source at
    a given local cooked time. Positive indicates local clock is FAST