diff --git a/include/sta/Bfs.hh b/include/sta/Bfs.hh
index bf198cf5..89080010 100644
--- a/include/sta/Bfs.hh
+++ b/include/sta/Bfs.hh
@@ -75,7 +75,7 @@ public:
   // Notify iterator that vertex will be deleted.
   void deleteVertexBefore(Vertex *vertex);
   void remove(Vertex *vertex);
-  void reportEntries();
+  void reportEntries() const;
 
   virtual bool hasNext();
   bool hasNext(Level to_level);
@@ -103,7 +103,7 @@ protected:
 			 Level level2) const = 0;
   virtual bool levelLessOrEqual(Level level1,
 				Level level2) const = 0;
-  virtual void incrLevel(Level &level) = 0;
+  virtual void incrLevel(Level &level) const = 0;
   void findNext(Level to_level);
   void deleteEntries();
 
@@ -139,7 +139,7 @@ protected:
 				Level level2) const;
   virtual bool levelLess(Level level1,
 			 Level level2) const;
-  virtual void incrLevel(Level &level);
+  virtual void incrLevel(Level &level) const;
 };
 
 class BfsBkwdIterator : public BfsIterator
@@ -159,7 +159,7 @@ protected:
 				Level level2) const;
   virtual bool levelLess(Level level1,
 			 Level level2) const;
-  virtual void incrLevel(Level &level);
+  virtual void incrLevel(Level &level) const;
 };
 
 } // namespace
diff --git a/liberty/LibertyReader.cc b/liberty/LibertyReader.cc
index c921ffd8..e7d64bcc 100644
--- a/liberty/LibertyReader.cc
+++ b/liberty/LibertyReader.cc
@@ -26,6 +26,7 @@
 
 #include <cctype>
 #include <cstdlib>
+#include <string>
 
 #include "EnumNameMap.hh"
 #include "Report.hh"
@@ -875,8 +876,23 @@ LibertyReader::visitCapacitiveLoadUnit(LibertyAttr *attr)
       LibertyAttrValueIterator value_iter(attr->values());
       if (value_iter.hasNext()) {
 	LibertyAttrValue *value = value_iter.next();
+	bool valid = false;
+	float scale;
 	if (value->isFloat()) {
-	  float scale = value->floatValue();
+	  scale = value->floatValue();
+	  valid = true;
+	}
+	else if (value->isString()) {
+	  try {
+	    scale = std::stof(value->stringValue());
+	    valid = true;
+	  }
+	  catch (...) {
+	    valid = false;
+	  }
+	}
+
+	if (valid) {
 	  if (value_iter.hasNext()) {
 	    value = value_iter.next();
 	    if (value->isString()) {
@@ -970,10 +986,24 @@ LibertyReader::visitVoltageMap(LibertyAttr *attr)
 	  const char *supply_name = value->stringValue();
 	  if (value_iter.hasNext()) {
 	    value = value_iter.next();
+            bool valid = false;
+	    float voltage;
 	    if (value->isFloat()) {
-	      float voltage = value->floatValue();
-	      library_->addSupplyVoltage(supply_name, voltage);
+	      voltage = value->floatValue();
+	      valid = true;
 	    }
+	    else if (value->isString()) {
+	      try {
+                voltage = std::stof(value->stringValue());
+                valid = true;
+	      }
+	      catch (...) {
+	        valid = false;
+	      }
+	    }
+
+	    if (valid)
+	      library_->addSupplyVoltage(supply_name, voltage);
 	    else
 	      libWarn(1166, attr, "voltage_map voltage is not a float.");
 	  }
diff --git a/search/Bfs.cc b/search/Bfs.cc
index 26472622..42cb4885 100644
--- a/search/Bfs.cc
+++ b/search/Bfs.cc
@@ -89,19 +89,16 @@ BfsIterator::clear()
 }
 
 void
-BfsIterator::reportEntries()
+BfsIterator::reportEntries() const
 {
-  Level level = first_level_;
-  while (levelLessOrEqual(level, last_level_)) {
-    VertexSeq &level_vertices = queue_[level];
+  for (Level level=first_level_; levelLessOrEqual(level, last_level_);incrLevel(level)){
+    const VertexSeq &level_vertices = queue_[level];
     if (!level_vertices.empty()) {
       report_->reportLine("Level %d", level);
-      for (Vertex *vertex : level_vertices) {
-	if (vertex)
-	  report_->reportLine(" %s", vertex->to_string(this).c_str());
-      }
+      for (Vertex *vertex : level_vertices)
+	report_->reportLine(" %s",
+			    vertex ? vertex->to_string(this).c_str() : "NULL");
     }
-    incrLevel(level);
   }
 }
 
@@ -255,9 +252,18 @@ void
 BfsIterator::findNext(Level to_level)
 {
   while (levelLessOrEqual(first_level_, last_level_)
-	 && levelLessOrEqual(first_level_, to_level)
-	 && queue_[first_level_].empty())
+	 && levelLessOrEqual(first_level_, to_level)) {
+    VertexSeq &level_vertices = queue_[first_level_];
+    // Skip null entries from deleted vertices.
+    while (!level_vertices.empty()) {
+      Vertex *vertex = level_vertices.back();
+      if (vertex == nullptr)
+	level_vertices.pop_back();
+      else
+	return;
+    }
     incrLevel(first_level_);
+  }
 }
 
 void
@@ -283,7 +289,7 @@ BfsIterator::enqueue(Vertex *vertex)
 bool
 BfsIterator::inQueue(Vertex *vertex)
 {
-  //  checkInQueue(vertex);
+  // checkInQueue(vertex);
   return vertex->bfsInQueue(bfs_index_);
 }
 
@@ -319,6 +325,9 @@ BfsIterator::remove(Vertex *vertex)
   Level level = vertex->level();
   if (vertex->bfsInQueue(bfs_index_)
       && static_cast<Level>(queue_.size()) > level) {
+    debugPrint(debug_, "bfs", 2, "remove %s",
+	       vertex->to_string(this).c_str());
+    printf("bfs remove %s\n", vertex->to_string(this).c_str());
     for (Vertex *&v : queue_[level]) {
       if (v == vertex) {
 	v = nullptr;
@@ -346,7 +355,7 @@ BfsFwdIterator::~BfsFwdIterator()
 }
 
 void
-BfsFwdIterator::incrLevel(Level &level)
+BfsFwdIterator::incrLevel(Level &level) const
 {
   level++;
 }
@@ -400,7 +409,7 @@ BfsBkwdIterator::~BfsBkwdIterator()
 }
 
 void
-BfsBkwdIterator::incrLevel(Level &level)
+BfsBkwdIterator::incrLevel(Level &level) const
 {
   level--;
 }
diff --git a/search/Levelize.cc b/search/Levelize.cc
index 7adef739..9effdad0 100644
--- a/search/Levelize.cc
+++ b/search/Levelize.cc
@@ -602,7 +602,7 @@ void
 Levelize::relevelizeFrom(Vertex *vertex)
 {
   if (levelized_) {
-    debugPrint(debug_, "levelize", 1, "relevelize from %s",
+    debugPrint(debug_, "levelize", 1, "level invalid from %s",
                vertex->to_string(this).c_str());
     relevelize_from_.insert(vertex);
     levels_valid_ = false;
@@ -649,8 +649,6 @@ Levelize::relevelize()
   ensureLatchLevels();
   levels_valid_ = true;
   relevelize_from_.clear();
-
-  checkLevels();
 }
 
 void
diff --git a/search/Levelize.hh b/search/Levelize.hh
index 68eece66..f0e5667b 100644
--- a/search/Levelize.hh
+++ b/search/Levelize.hh
@@ -70,9 +70,10 @@ public:
   // Set the observer for level changes.
   void setObserver(LevelizeObserver *observer);
   void checkLevels();
+  // Public for regression testing.
+  void levelize();
 
 protected:
-  void levelize();
   void findRoots();
   VertexSeq sortedRootsWithFanout();
   VertexSeq findTopologicalOrder();
diff --git a/search/Search.i b/search/Search.i
index 57b6fc2f..73f4761a 100644
--- a/search/Search.i
+++ b/search/Search.i
@@ -32,6 +32,7 @@
 #include "search/Levelize.hh"
 #include "search/ReportPath.hh"
 #include "PathExpanded.hh"
+#include "Bfs.hh"
 #include "Sta.hh"
 
 using namespace sta;
@@ -1128,6 +1129,32 @@ set_use_default_arrival_clock(bool enable)
   Sta::sta()->setUseDefaultArrivalClock(enable);
 }
 
+// For regression tests.
+void
+report_arrival_entries()
+{
+  Sta *sta = Sta::sta();
+  Search *search = sta->search();
+  search->arrivalIterator()->reportEntries();
+}
+
+// For regression tests.
+void
+report_required_entries()
+{
+  Sta *sta = Sta::sta();
+  Search *search = sta->search();
+  search->requiredIterator()->reportEntries();
+}
+
+// For regression tests.
+void
+levelize()
+{
+  Sta *sta = Sta::sta();
+  sta->levelize()->levelize();
+}
+
 %} // inline
 
 ////////////////////////////////////////////////////////////////
diff --git a/search/Sta.cc b/search/Sta.cc
index b7c28bbc..a766d927 100644
--- a/search/Sta.cc
+++ b/search/Sta.cc
@@ -4486,7 +4486,7 @@ Sta::disconnectPinBefore(const Pin *pin)
 void
 Sta::deleteEdge(Edge *edge)
 {
-  debugPrint(debug_, "network_edit", 1, "delete edge %s -> %s",
+  debugPrint(debug_, "network_edit", 2, "delete edge %s -> %s",
              edge->from(graph_)->name(sdc_network_),
              edge->to(graph_)->name(sdc_network_));
   Vertex *to = edge->to(graph_);
@@ -4568,6 +4568,8 @@ void
 Sta::deletePinBefore(const Pin *pin)
 {
   if (graph_) {
+    debugPrint(debug_, "network_edit", 1, "delete pin %s",
+	       sdc_network_->pathName(pin));
     if (network_->isLoad(pin)) {
       Vertex *vertex = graph_->pinLoadVertex(pin);
       if (vertex) {
diff --git a/test/liberty_float_as_str.lib b/test/liberty_float_as_str.lib
new file mode 100644
index 00000000..659f4ec4
--- /dev/null
+++ b/test/liberty_float_as_str.lib
@@ -0,0 +1,55 @@
+library (liberty_float_as_str) {
+  delay_model : "table_lookup";
+  simulation : false;
+  capacitive_load_unit ("1","fF");
+  leakage_power_unit : "1pW";
+  current_unit : "1A";
+  pulling_resistance_unit : "1kohm";
+  time_unit : "1ns";
+  voltage_unit : "1v";
+  library_features : "report_delay_calculation";
+  input_threshold_pct_rise : 50;
+  input_threshold_pct_fall : 50;
+  output_threshold_pct_rise : 50;
+  output_threshold_pct_fall : 50;
+  slew_lower_threshold_pct_rise : 30;
+  slew_lower_threshold_pct_fall : 30;
+  slew_upper_threshold_pct_rise : 70;
+  slew_upper_threshold_pct_fall : 70;
+  slew_derate_from_library : 1.0;
+  nom_process : 1.0;
+  nom_temperature : 85.0;
+  nom_voltage : 0.75;
+  voltage_map ("VDD", "0.65");
+  voltage_map ("VSS", "0");
+  voltage_map ("VCC", "-0.1");
+  voltage_map ("VBB", 0.1);
+  voltage_map ("GND", 0);
+
+  cell (my_inv) {
+    pin (A) {
+      capacitance : 1;
+      direction : "input";
+    }
+    pin (Y) {
+      function : "!A";
+      direction : "output";
+      timing () {
+        related_pin : "A";
+        timing_sense : "negative_unate";
+        cell_rise (scalar) {
+          values ("1");
+        }
+        cell_fall (scalar) {
+          values ("1");
+        }
+        rise_transition (scalar) {
+          values ("1");
+        }
+        fall_transition (scalar) {
+          values ("1");
+        }
+      }
+    }
+  }
+}
diff --git a/test/liberty_float_as_str.ok b/test/liberty_float_as_str.ok
new file mode 100644
index 00000000..8d63396d
--- /dev/null
+++ b/test/liberty_float_as_str.ok
@@ -0,0 +1,7 @@
+ time 1ns
+ capacitance 1fF
+ resistance 1kohm
+ voltage 1v
+ current 1A
+ power 1pW
+ distance 1um
diff --git a/test/liberty_float_as_str.tcl b/test/liberty_float_as_str.tcl
new file mode 100644
index 00000000..b3aeae01
--- /dev/null
+++ b/test/liberty_float_as_str.tcl
@@ -0,0 +1,3 @@
+# liberty with float as string in voltage_map and capacitive_load_unit
+read_liberty liberty_float_as_str.lib
+report_units
diff --git a/test/regression_vars.tcl b/test/regression_vars.tcl
index 2d71a1ac..9dcfd8f4 100644
--- a/test/regression_vars.tcl
+++ b/test/regression_vars.tcl
@@ -147,6 +147,7 @@ record_sta_tests {
   liberty_arcs_one2one_2
   liberty_backslash_eol
   liberty_ccsn
+  liberty_float_as_str
   liberty_latch3
   path_group_names
   prima3