diff --git a/sourcestats.c b/sourcestats.c
index 7dfc9db..900dc60 100644
--- a/sourcestats.c
+++ b/sourcestats.c
@@ -779,6 +779,22 @@ SST_SlewSamples(SST_Stats inst, struct timespec *when, double dfreq, double doff
 
 /* ================================================== */
 
+void
+SST_CorrectOffset(SST_Stats inst, double doffset)
+{
+  int i;
+
+  if (!inst->n_samples)
+    return;
+
+  for (i = -inst->runs_samples; i < inst->n_samples; i++)
+    inst->offsets[get_runsbuf_index(inst, i)] += doffset;
+
+  inst->estimated_offset += doffset;
+}
+
+/* ================================================== */
+
 void 
 SST_AddDispersion(SST_Stats inst, double dispersion)
 {
diff --git a/sourcestats.h b/sourcestats.h
index bb5fb71..7a551e6 100644
--- a/sourcestats.h
+++ b/sourcestats.h
@@ -102,6 +102,10 @@ SST_GetTrackingData(SST_Stats inst, struct timespec *ref_time,
 
 extern void SST_SlewSamples(SST_Stats inst, struct timespec *when, double dfreq, double doffset);
 
+/* This routine corrects already accumulated samples to improve the
+   frequency estimate when a new sample is accumulated */
+extern void SST_CorrectOffset(SST_Stats inst, 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);