diff --git a/dcalc/GraphDelayCalc1.cc b/dcalc/GraphDelayCalc1.cc
index 95f13931..7c699e04 100644
--- a/dcalc/GraphDelayCalc1.cc
+++ b/dcalc/GraphDelayCalc1.cc
@@ -476,7 +476,7 @@ FindNetDrvrs::operator()(Pin *pin)
 {
   Vertex *vertex = graph_->pinDrvrVertex(pin);
   if (isLeafDriver(pin, network_)
-      && !vertex->isRoot())
+      && !(vertex && vertex->isRoot()))
     drvr_pins_.insert(pin);
 }
 
diff --git a/search/Power.cc b/search/Power.cc
index 23831b32..a9e7edec 100644
--- a/search/Power.cc
+++ b/search/Power.cc
@@ -1034,7 +1034,7 @@ PwrActivity
 Power::findActivity(const Pin *pin)
 {
   Vertex *vertex = graph_->pinLoadVertex(pin);
-  if (search_->isClock(vertex))
+  if (vertex && search_->isClock(vertex))
     return PwrActivity(2.0, 0.5, PwrActivityOrigin::clock);
   else if (global_activity_.isSet())
     return global_activity_;