diff --git a/sdc/ExceptionPath.cc b/sdc/ExceptionPath.cc
index 78678649..d04946ff 100644
--- a/sdc/ExceptionPath.cc
+++ b/sdc/ExceptionPath.cc
@@ -1487,7 +1487,9 @@ ExceptionThru::deletePinEdges(const Pin *pin,
     }
     else {
       // erase prevents range iteration.
-      for (const EdgePins &edge_pins : *edges_) {
+      EdgePinsSet::Iterator edge_iter(edges_);
+      while (edge_iter.hasNext()) {
+        const EdgePins &edge_pins = edge_iter.next();
         if (edge_pins.first == pin
             || edge_pins.second == pin) {
           edges_->erase(edge_pins);
diff --git a/sdc/Sdc.cc b/sdc/Sdc.cc
index 9cdbb63a..2cf82c33 100644
--- a/sdc/Sdc.cc
+++ b/sdc/Sdc.cc
@@ -5663,12 +5663,15 @@ Sdc::connectPinAfter(const Pin *pin)
     PinSet *drvrs = network_->drivers(pin);
     for (ExceptionPath *exception : exceptions_) {
       ExceptionPt *first_pt = exception->firstPt();
-      for (ExceptionThru *thru : *exception->thrus()) {
-        if (thru->edges()) {
-          thru->connectPinAfter(drvrs, network_);
-          if (first_pt == thru)
-            recordExceptionEdges(exception, thru->edges(),
-                                 first_thru_edge_exceptions_);
+      ExceptionThruSeq *thrus = exception->thrus();
+      if (thrus) {
+        for (ExceptionThru *thru : *exception->thrus()) {
+          if (thru->edges()) {
+            thru->connectPinAfter(drvrs, network_);
+            if (first_pt == thru)
+              recordExceptionEdges(exception, thru->edges(),
+                                   first_thru_edge_exceptions_);
+          }
         }
       }
     }
@@ -5681,12 +5684,15 @@ Sdc::disconnectPinBefore(const Pin *pin)
   if (have_thru_hpin_exceptions_) {
     for (ExceptionPath *exception : exceptions_) {
       ExceptionPt *first_pt = exception->firstPt();
-      for (ExceptionThru *thru : *exception->thrus()) {
-        if (thru->edges()) {
-          thru->disconnectPinBefore(pin, network_);
-          if (thru == first_pt)
-            recordExceptionEdges(exception, thru->edges(),
-                                 first_thru_edge_exceptions_);
+      ExceptionThruSeq *thrus = exception->thrus();
+      if (thrus) {
+        for (ExceptionThru *thru : *exception->thrus()) {
+          if (thru->edges()) {
+            thru->disconnectPinBefore(pin, network_);
+            if (thru == first_pt)
+              recordExceptionEdges(exception, thru->edges(),
+                                   first_thru_edge_exceptions_);
+          }
         }
       }
     }