diff --git a/doc/CodingGuidelines.txt b/doc/CodingGuidelines.txt
index 1c6f8dce..001e5900 100644
--- a/doc/CodingGuidelines.txt
+++ b/doc/CodingGuidelines.txt
@@ -8,6 +8,7 @@ member variable - snake case with trailing underscore (member_variable_)
                   Trailing underscore prevents conflict with accessor 
                   member function name.
 function - lower camel case (functionName)
+variable - snake case
 comments - use capitalized sentences that end with periods
 
 C++ code files should use a .cc file extension
@@ -55,7 +56,7 @@ this:
 instead, write this:
 
      foo = (char *) malloc (sizeof *foo);
-     if (foo == 0)
+     if (foo == nullptr)
        fatal ("virtual memory exhausted");
 
 
diff --git a/include/sta/Sta.hh b/include/sta/Sta.hh
index b5aadae3..30debd8f 100644
--- a/include/sta/Sta.hh
+++ b/include/sta/Sta.hh
@@ -1236,7 +1236,7 @@ public:
   void setCmdCorner(Corner *corner);
   Corner *findCorner(const char *corner_name);
   bool multiCorner();
-  void makeCorners(StringSet *corner_names);
+  virtual void makeCorners(StringSet *corner_names);
   // Find all arc delays and vertex slews with delay calculator.
   virtual void findDelays();
   // Find arc delays and vertex slews thru to level of to_vertex.
diff --git a/liberty/Liberty.cc b/liberty/Liberty.cc
index 5e0edffa..8bad4c35 100644
--- a/liberty/Liberty.cc
+++ b/liberty/Liberty.cc
@@ -1852,10 +1852,15 @@ LibertyCell::makeLatchEnable(LibertyPort *d,
   latch_d_to_q_map_[d_to_q] = latch_enable;
   latch_check_map_[setup_check] = latch_enable;
   latch_data_ports_.insert(d);
-  debugPrint(debug, "liberty", 2, "latch d=%s en=%s %s q=%s",
+  debugPrint(debug, "liberty_latch", 1,
+             "latch %s -> %s | %s %s -> %s | %s %s -> %s setup",
              d->name(),
+             q->name(),
              en->name(),
-             en_rf->name(),
+             en_rf->shortName(),
+             q->name(),
+             en->name(),
+             setup_check->arcs()[0]->fromEdge()->asRiseFall()->shortName(),
              q->name());
   return latch_enable;
 }
diff --git a/sdf/SdfReader.cc b/sdf/SdfReader.cc
index 195f51be..859ba47c 100644
--- a/sdf/SdfReader.cc
+++ b/sdf/SdfReader.cc
@@ -425,13 +425,15 @@ void
 SdfReader::timingCheck(TimingRole *role, SdfPortSpec *data_edge,
 		       SdfPortSpec *clk_edge, SdfTriple *triple)
 {
-  const char *data_port_name = data_edge->port();
-  const char *clk_port_name = clk_edge->port();
-  Cell *cell = network_->cell(instance_);
-  Port *data_port = findPort(cell, data_port_name);
-  Port *clk_port = findPort(cell, clk_port_name);
-  if (data_port && clk_port)
-    timingCheck1(role, data_port, data_edge, clk_port, clk_edge, triple);
+  if (instance_) {
+    const char *data_port_name = data_edge->port();
+    const char *clk_port_name = clk_edge->port();
+    Cell *cell = network_->cell(instance_);
+    Port *data_port = findPort(cell, data_port_name);
+    Port *clk_port = findPort(cell, clk_port_name);
+    if (data_port && clk_port)
+      timingCheck1(role, data_port, data_edge, clk_port, clk_edge, triple);
+  }
   deletePortSpec(data_edge);
   deletePortSpec(clk_edge);
   deleteTriple(triple);