diff --git a/search/Power.cc b/search/Power.cc
index 2e4e3e97..fe0d1708 100644
--- a/search/Power.cc
+++ b/search/Power.cc
@@ -1,18 +1,10 @@
-// OpenSTA, Static Timing Analyzer
+// Parallax Static Timing Analyzer
 // Copyright (c) 2019, Parallax Software, Inc.
+// All rights reserved.
 // 
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-// 
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-// 
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+// No part of this document may be copied, transmitted or
+// disclosed in any form or fashion without the express
+// written consent of Parallax Software, Inc.
 
 #include <algorithm> // max
 #include "Machine.hh"
@@ -335,6 +327,8 @@ Power::evalActivity(FuncExpr *expr,
     Pin *pin = network_->findPin(inst, expr->port()->name());
     if (pin)
       return findActivity(pin);
+    else
+      return PwrActivity(0.0, 0.0, PwrActivityOrigin::constant);
   }
   case FuncExpr::op_not: {
     PwrActivity activity1 = evalActivity(expr->left(), inst);
@@ -528,6 +522,13 @@ Power::findInstClk(const Instance *inst)
   return inst_clk;
 }
 
+void
+check(float x)
+{
+  if (std::isnan(x))
+    printf("luse\n");
+}
+
 void
 Power::findInternalPower(const Pin *to_pin,
 			 const LibertyPort *to_port,
@@ -569,49 +570,62 @@ Power::findInternalPower(const Pin *to_pin,
       if ((when && internalPowerMissingWhen(cell, to_port, related_pg_pin))
 	  || pgNameVoltage(cell, related_pg_pin, dcalc_ap) != 0.0) {
 	const Pin *from_pin = network_->findPin(inst, from_port);
-	Vertex *from_vertex = graph_->pinLoadVertex(from_pin);
-	float duty;
-	if (infered_when) {
-	  PwrActivity from_activity = findActivity(from_pin);
-	  PwrActivity to_activity = findActivity(to_pin);
-	  float duty1 = evalActivity(infered_when, inst).duty();
-	  duty = from_activity.activity() / to_activity.activity() * duty1;
-	}
-	else if (when)
-	  duty = evalActivity(when, inst).duty();
-	else if (search_->isClock(from_vertex))
-	  duty = 1.0;
-	else
-	  duty = 0.5;
-	float port_energy = 0.0;
-	TransRiseFallIterator tr_iter;
-	while (tr_iter.hasNext()) {
-	  TransRiseFall *to_tr = tr_iter.next();
-	  // Should use unateness to find from_tr.
-	  TransRiseFall *from_tr = to_tr;
-	  float slew = delayAsFloat(graph_->slew(from_vertex,
-						 from_tr,
-						 dcalc_ap->index()));
-	  float table_energy = pwr->power(to_tr, pvt, slew, load_cap);
-	  float tr_energy = table_energy * duty;
-	  debugPrint4(debug_, "power", 3,  " %s energy = %9.2e * %.2f = %9.2e\n",
-		      to_tr->shortName(),
-		      table_energy,
+	if (from_pin) {
+	  Vertex *from_vertex = graph_->pinLoadVertex(from_pin);
+	  float duty;
+	  if (infered_when) {
+	    PwrActivity from_activity = findActivity(from_pin);
+	    PwrActivity to_activity = findActivity(to_pin);
+	    float duty1 = evalActivity(infered_when, inst).duty();
+	    check(from_activity.activity());
+	    check(to_activity.activity());
+	    check(duty1);
+	    if (to_activity.activity() == 0.0)
+	      duty = 0.0;
+	    else
+	      duty = from_activity.activity() / to_activity.activity() * duty1;
+	    check(duty);
+	  }
+	  else if (when)
+	    duty = evalActivity(when, inst).duty();
+	  else if (search_->isClock(from_vertex))
+	    duty = 1.0;
+	  else
+	    duty = 0.5;
+	  check(duty);
+	  float port_energy = 0.0;
+	  TransRiseFallIterator tr_iter;
+	  while (tr_iter.hasNext()) {
+	    TransRiseFall *to_tr = tr_iter.next();
+	    // Should use unateness to find from_tr.
+	    TransRiseFall *from_tr = to_tr;
+	    float slew = delayAsFloat(graph_->slew(from_vertex,
+						   from_tr,
+						   dcalc_ap->index()));
+	    float table_energy = pwr->power(to_tr, pvt, slew, load_cap);
+	    float tr_energy = table_energy * duty;
+	    debugPrint4(debug_, "power", 3,  " %s energy = %9.2e * %.2f = %9.2e\n",
+			to_tr->shortName(),
+			table_energy,
+			duty,
+			tr_energy);
+	    check(slew);
+	    check(table_energy);
+	    check(tr_energy);
+	    port_energy += tr_energy;
+	  }
+	  float port_internal = port_energy * to_activity.activity();
+	  debugPrint8(debug_, "power", 2,  " %s -> %s %s  %.2f %.2f %9.2e %9.2e %s\n",
+		      from_port->name(),
+		      to_port->name(),
+		      when ? when->asString() : (infered_when ? infered_when->asString() : "    "),
+		      to_activity.activity() * 1e-9,
 		      duty,
-		      tr_energy);
-	  port_energy += tr_energy;
+		      port_energy,
+		      port_internal,
+		      related_pg_pin ? related_pg_pin : "no pg_pin");
+	  internal += port_internal;
 	}
-	float port_internal = port_energy * to_activity.activity();
-	debugPrint8(debug_, "power", 2,  " %s -> %s %s  %.2f %.2f %9.2e %9.2e %s\n",
-		    from_port->name(),
-		    to_port->name(),
-		    when ? when->asString() : (infered_when ? infered_when->asString() : "    "),
-		    to_activity.activity() * 1e-9,
-		    duty,
-		    port_energy,
-		    port_internal,
-		    related_pg_pin ? related_pg_pin : "no pg_pin");
-	internal += port_internal;
       }
       if (infered_when)
 	infered_when->deleteSubexprs();
diff --git a/search/Property.cc b/search/Property.cc
index 7598298d..42277efb 100644
--- a/search/Property.cc
+++ b/search/Property.cc
@@ -640,7 +640,7 @@ portSlackProperty(const Port *port,
 PropertyValue
 getProperty(const LibertyPort *port,
 	    const char *property,
-	    Sta *)
+	    Sta *sta)
 {
   if (stringEqual(property, "name"))
     return PropertyValue(port->name());
@@ -648,6 +648,10 @@ getProperty(const LibertyPort *port,
     return PropertyValue(port->name());
   else if (stringEqual(property, "direction"))
     return PropertyValue(port->direction()->name());
+  else if (stringEqual(property, "capacitance")) {
+    float cap = port->capacitance(TransRiseFall::rise(), MinMax::max());
+    return PropertyValue(sta->units()->capacitanceUnit()->asString(cap, 6));
+  }
   else
     throw PropertyUnknown("liberty port", property);
 }
@@ -863,7 +867,7 @@ getProperty(Clock *clk,
       || stringEqual(property, "full_name"))
     return PropertyValue(clk->name());
   else if (stringEqual(property, "period"))
-    return PropertyValue(sta->units()->timeUnit()->asString(clk->period(), 8));
+    return PropertyValue(sta->units()->timeUnit()->asString(clk->period(), 6));
   else if (stringEqual(property, "sources"))
     return PropertyValue(clk->pins());
   else if (stringEqual(property, "propagated"))
diff --git a/tcl/StaTcl.i b/tcl/StaTcl.i
index 5b2afce1..6bfd8935 100644
--- a/tcl/StaTcl.i
+++ b/tcl/StaTcl.i
@@ -1533,7 +1533,7 @@ using namespace sta;
     Tcl_SetResult(interp, const_cast<char*>(value.stringValue()), TCL_VOLATILE);
     break;
   case PropertyValue::Type::type_float: {
-    char *float_string = stringPrint("%.5f", value.floatValue());
+    char *float_string = stringPrint("%.6e", value.floatValue());
     Tcl_SetResult(interp, float_string, TCL_VOLATILE);
     stringDelete(float_string);
   }