diff --git a/include/sta/Search.hh b/include/sta/Search.hh
index 3f4331ec..72d00664 100644
--- a/include/sta/Search.hh
+++ b/include/sta/Search.hh
@@ -19,7 +19,7 @@
 #include <mutex>
 
 #include "MinMax.hh"
-#include "HashSet.hh"
+#include "UnorderedSet.hh"
 #include "Transition.hh"
 #include "LibertyClass.hh"
 #include "NetworkClass.hh"
@@ -55,8 +55,8 @@ class Genclks;
 class Corner;
 
 typedef Set<ClkInfo*, ClkInfoLess> ClkInfoSet;
-typedef HashSet<Tag*, TagHash, TagEqual> TagHashSet;
-typedef HashSet<TagGroup*, TagGroupHash, TagGroupEqual> TagGroupSet;
+typedef UnorderedSet<Tag*, TagHash, TagEqual> TagSet;
+typedef UnorderedSet<TagGroup*, TagGroupHash, TagGroupEqual> TagGroupSet;
 typedef Map<Vertex*, Slack> VertexSlackMap;
 typedef Vector<VertexSlackMap> VertexSlackMapSeq;
 typedef Vector<WorstSlacks> WorstSlacksSeq;
@@ -568,7 +568,7 @@ protected:
   ClkInfoSet *clk_info_set_;
   std::mutex clk_info_lock_;
   // Use pointer to tag set so Tag.hh does not need to be included.
-  TagHashSet *tag_set_;
+  TagSet *tag_set_;
   // Entries in tags_ may be missing where previous filter tags were deleted.
   TagIndex tag_capacity_;
   Tag **tags_;
diff --git a/include/sta/UnorderedSet.hh b/include/sta/UnorderedSet.hh
index b7860693..4138c1e6 100644
--- a/include/sta/UnorderedSet.hh
+++ b/include/sta/UnorderedSet.hh
@@ -31,6 +31,11 @@ public:
   {
   }
 
+  explicit UnorderedSet(size_t size) :
+    std::unordered_set<KEY, HASH, EQUAL>(size)
+  {
+  }
+
   explicit UnorderedSet(size_t size,
 			const HASH &hash,
 			const EQUAL &equal) :
diff --git a/search/Search.cc b/search/Search.cc
index 6f3fbd75..21bc85e6 100644
--- a/search/Search.cc
+++ b/search/Search.cc
@@ -235,14 +235,14 @@ Search::init(StaState *sta)
   arrival_iter_ = new BfsFwdIterator(BfsIndex::arrival, nullptr, sta);
   required_iter_ = new BfsBkwdIterator(BfsIndex::required, search_adj_, sta);
   tag_capacity_ = 127;
-  tag_set_ = new TagHashSet(tag_capacity_, false);
+  tag_set_ = new TagSet(tag_capacity_);
   clk_info_set_ = new ClkInfoSet(ClkInfoLess(sta));
   tag_next_ = 0;
   tags_ = new Tag*[tag_capacity_];
   tag_group_capacity_ = 127;
   tag_groups_ = new TagGroup*[tag_group_capacity_];
   tag_group_next_ = 0;
-  tag_group_set_ = new TagGroupSet(tag_group_capacity_, false);
+  tag_group_set_ = new TagGroupSet(tag_group_capacity_);
   visit_path_ends_ = new VisitPathEnds(this);
   gated_clk_ = new GatedClk(this);
   path_groups_ = nullptr;
@@ -2793,13 +2793,17 @@ Search::reportTagGroups() const
       report_->reportLine("Group %4u hash = %4lu (%4lu)",
                           i,
                           tag_group->hash(),
-                          tag_group->hash() % tag_group_set_->capacity());
+                          tag_group->hash() % tag_group_set_->bucket_count());
       tag_group->reportArrivalMap(this);
     }
   }
-  size_t long_hash = tag_group_set_->longestBucketHash();
-  report_->reportLine("Longest hash bucket length %d hash=%lu",
-                      tag_group_set_->bucketLength(long_hash),
+  size_t long_hash = 0;
+  for (size_t i = 0; i < tag_group_set_->bucket_count(); i++) {
+    if (tag_group_set_->bucket_size(i) > long_hash)
+      long_hash = i;
+  }
+  report_->reportLine("Longest hash bucket length %zu hash=%zu",
+                      tag_group_set_->bucket_size(long_hash),
                       long_hash);
 }
 
@@ -2903,9 +2907,13 @@ Search::reportTags() const
     if (tag)
       report_->reportLine("%s", tag->asString(this)) ;
   }
-  size_t long_hash = tag_set_->longestBucketHash();
-  report_->reportLine("Longest hash bucket length %d hash=%zu",
-                      tag_set_->bucketLength(long_hash),
+  size_t long_hash = 0;
+  for (size_t i = 0; i < tag_set_->bucket_count(); i++) {
+    if (tag_set_->bucket_size(i) > long_hash)
+      long_hash = i;
+  }
+  report_->reportLine("Longest hash bucket length %zu hash=%zu",
+                      tag_set_->bucket_size(long_hash),
                       long_hash);
 }
 
diff --git a/search/Tag.cc b/search/Tag.cc
index 61a4ff91..9835d5dd 100644
--- a/search/Tag.cc
+++ b/search/Tag.cc
@@ -654,14 +654,14 @@ tagStateEqualCrpr(const Tag *tag1,
 ////////////////////////////////////////////////////////////////
 
 size_t
-TagHash::operator()(const Tag *tag)
+TagHash::operator()(const Tag *tag) const
 {
   return tag->hash();
 }
 
 bool
 TagEqual::operator()(const Tag *tag1,
-		     const Tag *tag2)
+		     const Tag *tag2) const
 {
   return tagEqual(tag1, tag2);
 }
diff --git a/search/Tag.hh b/search/Tag.hh
index 8b1fdbe1..c9c9564c 100644
--- a/search/Tag.hh
+++ b/search/Tag.hh
@@ -120,14 +120,14 @@ public:
 class TagHash
 {
 public:
-  size_t operator()(const Tag *tag);
+  size_t operator()(const Tag *tag) const;
 };
 
 class TagEqual
 {
 public:
   bool operator()(const Tag *tag1,
-		  const Tag *tag2);
+		  const Tag *tag2) const;
 };
 
 int