diff --git a/src/db/db/dbHierProcessor.h b/src/db/db/dbHierProcessor.h
index 866137bbc..5bf25384b 100644
--- a/src/db/db/dbHierProcessor.h
+++ b/src/db/db/dbHierProcessor.h
@@ -51,12 +51,39 @@ namespace std
     }
   };
 
-  template <class Polygon, class Trans>
-  struct hash<db::polygon_ref<Polygon, Trans> >
+  template <class Shape, class Trans>
+  struct hash<db::shape_ref<Shape, Trans> >
   {
-    size_t operator() (const db::polygon_ref<Polygon, Trans> &o) const
+    size_t operator() (const db::shape_ref<Shape, Trans> &o) const
     {
-      return hfunc (size_t (o.ptr ()), std::hash<Trans> () (o.trans ()));
+      return hfunc (std::hash<Shape> () (*o.ptr ()), std::hash<Trans> () (o.trans ()));
+    }
+  };
+
+  template <class Shape, class Trans>
+  struct hash<db::polygon_ref<Shape, Trans> >
+  {
+    size_t operator() (const db::polygon_ref<Shape, Trans> &o) const
+    {
+      return std::hash<db::shape_ref<Shape, Trans> > () (o);
+    }
+  };
+
+  template <class Shape, class Trans>
+  struct hash<db::path_ref<Shape, Trans> >
+  {
+    size_t operator() (const db::path_ref<Shape, Trans> &o) const
+    {
+      return std::hash<db::shape_ref<Shape, Trans> > () (o);
+    }
+  };
+
+  template <class Shape, class Trans>
+  struct hash<db::text_ref<Shape, Trans> >
+  {
+    size_t operator() (const db::text_ref<Shape, Trans> &o) const
+    {
+      return std::hash<db::shape_ref<Shape, Trans> > () (o);
     }
   };
 
diff --git a/src/db/db/dbNetlistDeviceExtractor.cc b/src/db/db/dbNetlistDeviceExtractor.cc
index 07103f2a1..a0d40cb31 100644
--- a/src/db/db/dbNetlistDeviceExtractor.cc
+++ b/src/db/db/dbNetlistDeviceExtractor.cc
@@ -173,6 +173,7 @@ void NetlistDeviceExtractor::extract_without_initialize (db::Layout &layout, db:
   all_called_cells.clear ();
 
   //  build the device clusters
+
   db::Connectivity device_conn = get_connectivity (layout, layers);
   db::hier_clusters<shape_type> device_clusters;
   device_clusters.build (layout, cell, shape_iter_flags, device_conn);
diff --git a/src/db/unit_tests/dbNetlistExtractorTests.cc b/src/db/unit_tests/dbNetlistExtractorTests.cc
index add58495f..22d590b75 100644
--- a/src/db/unit_tests/dbNetlistExtractorTests.cc
+++ b/src/db/unit_tests/dbNetlistExtractorTests.cc
@@ -496,46 +496,46 @@ TEST(2_DeviceAndNetExtractionFlat)
   //  happen to be the same because they share the same label.
   EXPECT_EQ (nl.to_string (),
     "Circuit RINGO ():\n"
-    "  DPMOS $1 (S='IN,FB',G='IN,OUT',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
-    "  DPMOS $2 (S=VDD,G='IN,FB',D='OUT,OSC') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
-    "  DPMOS $3 (S=$18,G='IN,OUT',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
-    "  DPMOS $4 (S=VDD,G=$18,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
-    "  DPMOS $5 (S=$16,G='IN,OUT',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
-    "  DPMOS $6 (S=VDD,G=$16,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
-    "  DPMOS $7 (S=$14,G='IN,OUT',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
-    "  DPMOS $8 (S=VDD,G=$14,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
-    "  DPMOS $9 (S=$12,G='IN,OUT',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
-    "  DPMOS $10 (S=VDD,G=$12,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
-    "  DPMOS $11 (S=$4,G='IN,OUT',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
-    "  DPMOS $12 (S=VDD,G=$4,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
-    "  DPMOS $13 (S=$8,G='IN,OUT',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
-    "  DPMOS $14 (S=VDD,G=$8,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
+    "  DPMOS $1 (S=$16,G='IN,OUT',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
+    "  DPMOS $2 (S=VDD,G=$16,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
+    "  DPMOS $3 (S=$14,G='IN,OUT',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
+    "  DPMOS $4 (S=VDD,G=$14,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
+    "  DPMOS $5 (S=$12,G='IN,OUT',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
+    "  DPMOS $6 (S=VDD,G=$12,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
+    "  DPMOS $7 (S='IN,FB',G='IN,OUT',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
+    "  DPMOS $8 (S=VDD,G='IN,FB',D='OUT,OSC') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
+    "  DPMOS $9 (S=$4,G='IN,OUT',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
+    "  DPMOS $10 (S=VDD,G=$4,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
+    "  DPMOS $11 (S=$8,G='IN,OUT',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
+    "  DPMOS $12 (S=VDD,G=$8,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
+    "  DPMOS $13 (S=$2,G='IN,FB',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
+    "  DPMOS $14 (S=VDD,G=$2,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
     "  DPMOS $15 (S=$6,G='IN,OUT',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
     "  DPMOS $16 (S=VDD,G=$6,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
-    "  DPMOS $17 (S=$2,G='IN,FB',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
-    "  DPMOS $18 (S=VDD,G=$2,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
+    "  DPMOS $17 (S=$18,G='IN,OUT',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
+    "  DPMOS $18 (S=VDD,G=$18,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
     "  DPMOS $19 (S=$10,G='IN,OUT',D=VDD) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
     "  DPMOS $20 (S=VDD,G=$10,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
     "  DNMOS $21 (S='IN,FB',G='IN,OUT',D=VSS) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
     "  DNMOS $22 (S=VSS,G='IN,FB',D='OUT,OSC') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
-    "  DNMOS $23 (S=$16,G='IN,OUT',D=VSS) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
-    "  DNMOS $24 (S=VSS,G=$16,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
+    "  DNMOS $23 (S=$18,G='IN,OUT',D=VSS) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
+    "  DNMOS $24 (S=VSS,G=$18,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
     "  DNMOS $25 (S=$14,G='IN,OUT',D=VSS) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
     "  DNMOS $26 (S=VSS,G=$14,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
     "  DNMOS $27 (S=$12,G='IN,OUT',D=VSS) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
     "  DNMOS $28 (S=VSS,G=$12,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
     "  DNMOS $29 (S=$4,G='IN,OUT',D=VSS) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
     "  DNMOS $30 (S=VSS,G=$4,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
-    "  DNMOS $31 (S=$18,G='IN,OUT',D=VSS) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
-    "  DNMOS $32 (S=VSS,G=$18,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
-    "  DNMOS $33 (S=$2,G='IN,FB',D=VSS) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
-    "  DNMOS $34 (S=VSS,G=$2,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
-    "  DNMOS $35 (S=$10,G='IN,OUT',D=VSS) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
-    "  DNMOS $36 (S=VSS,G=$10,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
-    "  DNMOS $37 (S=$6,G='IN,OUT',D=VSS) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
-    "  DNMOS $38 (S=VSS,G=$6,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
-    "  DNMOS $39 (S=$8,G='IN,OUT',D=VSS) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
-    "  DNMOS $40 (S=VSS,G=$8,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
+    "  DNMOS $31 (S=$2,G='IN,FB',D=VSS) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
+    "  DNMOS $32 (S=VSS,G=$2,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
+    "  DNMOS $33 (S=$8,G='IN,OUT',D=VSS) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
+    "  DNMOS $34 (S=VSS,G=$8,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
+    "  DNMOS $35 (S=$6,G='IN,OUT',D=VSS) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
+    "  DNMOS $36 (S=VSS,G=$6,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
+    "  DNMOS $37 (S=$16,G='IN,OUT',D=VSS) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
+    "  DNMOS $38 (S=VSS,G=$16,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
+    "  DNMOS $39 (S=$10,G='IN,OUT',D=VSS) [L=0.25,W=0.95,AS=0.49875,AD=0.26125]\n"
+    "  DNMOS $40 (S=VSS,G=$10,D='IN,OUT') [L=0.25,W=0.95,AS=0.26125,AD=0.49875]\n"
   );
 
   //  compare the collected test data