diff --git a/conf.c b/conf.c
index aafdba3..6fa5eee 100644
--- a/conf.c
+++ b/conf.c
@@ -676,7 +676,7 @@ parse_refclock(char *line)
   int n, poll, dpoll, filter_length, pps_rate, min_samples, max_samples, sel_options;
   int max_lock_age, pps_forced;
   uint32_t ref_id, lock_ref_id;
-  double offset, delay, precision, max_dispersion;
+  double offset, delay, precision, max_dispersion, pulse_width;
   char *p, *cmd, *name, *param;
   unsigned char ref[5];
   RefclockParameters *refclock;
@@ -693,6 +693,7 @@ parse_refclock(char *line)
   delay = 1e-9;
   precision = 0.0;
   max_dispersion = 0.0;
+  pulse_width = 0.0;
   ref_id = 0;
   max_lock_age = 2;
   lock_ref_id = 0;
@@ -766,6 +767,9 @@ parse_refclock(char *line)
     } else if (!strcasecmp(cmd, "maxdispersion")) {
       if (sscanf(line, "%lf%n", &max_dispersion, &n) != 1)
         break;
+    } else if (!strcasecmp(cmd, "width")) {
+      if (sscanf(line, "%lf%n", &pulse_width, &n) != 1)
+        break;
     } else if (!strcasecmp(cmd, "noselect")) {
       n = 0;
       sel_options |= SRC_SELECT_NOSELECT;
@@ -804,6 +808,7 @@ parse_refclock(char *line)
   refclock->delay = delay;
   refclock->precision = precision;
   refclock->max_dispersion = max_dispersion;
+  refclock->pulse_width = pulse_width;
   refclock->ref_id = ref_id;
   refclock->max_lock_age = max_lock_age;
   refclock->lock_ref_id = lock_ref_id;
diff --git a/refclock.c b/refclock.c
index 0cdc061..e89b485 100644
--- a/refclock.c
+++ b/refclock.c
@@ -85,6 +85,7 @@ struct RCL_Instance_Record {
   double offset;
   double delay;
   double precision;
+  double pulse_width;
   SCH_TimeoutID timeout_id;
   SRC_Instance source;
 };
@@ -208,6 +209,7 @@ RCL_AddRefclock(RefclockParameters *params)
   inst->delay = params->delay;
   if (params->precision > 0.0)
     inst->precision = params->precision;
+  inst->pulse_width = params->pulse_width;
   inst->timeout_id = -1;
   inst->source = NULL;
 
@@ -415,6 +417,27 @@ RCL_AddPulse(RCL_Instance instance, struct timespec *pulse_time, double second)
   return RCL_AddCookedPulse(instance, &cooked_time, second, dispersion, correction);
 }
 
+static int
+check_pulse_edge(RCL_Instance instance, double offset, double distance)
+{
+  double max_error;
+
+  if (instance->pulse_width <= 0.0)
+    return 1;
+
+  max_error = 1.0 / instance->pps_rate - instance->pulse_width;
+  max_error = MIN(instance->pulse_width, max_error);
+  max_error *= 0.5;
+
+  if (fabs(offset) > max_error || distance > max_error) {
+      DEBUG_LOG("refclock pulse ignored offset=%.9f distance=%.9f max_error=%.9f",
+                offset, distance, max_error);
+      return 0;
+  }
+
+  return 1;
+}
+
 int
 RCL_AddCookedPulse(RCL_Instance instance, struct timespec *cooked_time,
                    double second, double dispersion, double raw_correction)
@@ -476,6 +499,9 @@ RCL_AddCookedPulse(RCL_Instance instance, struct timespec *cooked_time,
       return 0;
     }
 
+    if (!check_pulse_edge(instance, ref_offset - offset, 0.0))
+      return 0;
+
     leap = lock_refclock->leap_status;
 
     DEBUG_LOG("refclock pulse offset=%.9f offdiff=%.9f samplediff=%.9f",
@@ -500,6 +526,9 @@ RCL_AddCookedPulse(RCL_Instance instance, struct timespec *cooked_time,
       filter_reset(&instance->filter);
       return 0;
     }
+
+    if (!check_pulse_edge(instance, offset, distance))
+      return 0;
   }
 
   filter_add_sample(&instance->filter, cooked_time, offset, dispersion);
diff --git a/refclock.h b/refclock.h
index 0eb4caa..40ce12d 100644
--- a/refclock.h
+++ b/refclock.h
@@ -49,6 +49,7 @@ typedef struct {
   double delay;
   double precision;
   double max_dispersion;
+  double pulse_width;
 } RefclockParameters;
 
 typedef struct RCL_Instance_Record *RCL_Instance;