diff --git a/dcalc/DcalcAnalysisPt.cc b/dcalc/DcalcAnalysisPt.cc
index 2dfb635a..518edd4e 100644
--- a/dcalc/DcalcAnalysisPt.cc
+++ b/dcalc/DcalcAnalysisPt.cc
@@ -54,7 +54,7 @@ DcalcAnalysisPt::setCheckClkSlewIndex(DcalcAPIndex index)
 int 
 DcalcAnalysisPt::libertyIndex() const
 {
-  return index_; // same for now
+  return corner_->libertyIndex(min_max_);
 }
 
 } // namespace
diff --git a/include/sta/Sta.hh b/include/sta/Sta.hh
index 1f887d5b..35eea33a 100644
--- a/include/sta/Sta.hh
+++ b/include/sta/Sta.hh
@@ -951,6 +951,11 @@ public:
                                  const MinMax *min_max);
   PathRef vertexWorstArrivalPath(Vertex *vertex,
                                  const MinMax *min_max);
+  PathRef vertexWorstRequiredPath(Vertex *vertex,
+                                  const RiseFall *rf,
+                                  const MinMax *min_max);
+  PathRef vertexWorstRequiredPath(Vertex *vertex,
+                                  const MinMax *min_max);
   PathRef vertexWorstSlackPath(Vertex *vertex,
                                const MinMax *min_max);
   PathRef vertexWorstSlackPath(Vertex *vertex,
diff --git a/search/Sta.cc b/search/Sta.cc
index 727be7e0..359a3f4d 100644
--- a/search/Sta.cc
+++ b/search/Sta.cc
@@ -2677,6 +2677,13 @@ Sta::vertexPathIterator(Vertex *vertex,
   return new VertexPathIterator(vertex, rf, min_max, this);
 }
 
+PathRef
+Sta::vertexWorstArrivalPath(Vertex *vertex,
+			    const MinMax *min_max)
+{
+  return vertexWorstArrivalPath(vertex, nullptr, min_max);
+}
+
 PathRef
 Sta::vertexWorstArrivalPath(Vertex *vertex,
 			    const RiseFall *rf,
@@ -2698,10 +2705,31 @@ Sta::vertexWorstArrivalPath(Vertex *vertex,
 }
 
 PathRef
-Sta::vertexWorstArrivalPath(Vertex *vertex,
-			    const MinMax *min_max)
+Sta::vertexWorstRequiredPath(Vertex *vertex,
+                             const MinMax *min_max)
 {
-  return vertexWorstArrivalPath(vertex, nullptr, min_max);
+  return vertexWorstRequiredPath(vertex, nullptr, min_max);
+}
+
+PathRef
+Sta::vertexWorstRequiredPath(Vertex *vertex,
+                             const RiseFall *rf,
+                             const MinMax *min_max)
+{
+  PathRef worst_path;
+  const MinMax *req_min_max = min_max->opposite();
+  Arrival worst_req = req_min_max->initValue();
+  VertexPathIterator path_iter(vertex, rf, min_max, this);
+  while (path_iter.hasNext()) {
+    PathVertex *path = path_iter.next();
+    const Required path_req = path->required(this);
+    if (!path->tag(this)->isGenClkSrcPath()
+	&& delayGreater(path_req, worst_req, req_min_max, this)) {
+      worst_req = path_req;
+      worst_path.init(path);
+    }
+  }
+  return worst_path;
 }
 
 PathRef