diff --git a/include/sta/ExceptionPath.hh b/include/sta/ExceptionPath.hh
index 92e8c47a..c50b5c82 100644
--- a/include/sta/ExceptionPath.hh
+++ b/include/sta/ExceptionPath.hh
@@ -49,6 +49,8 @@ public:
 		int priority,
 		const char *comment);
   virtual ~ExceptionPath();
+  size_t id() const { return id_; }
+  void setId(size_t id);
   virtual bool isFalse() const { return false; }
   virtual bool isLoop() const { return false; }
   virtual bool isMultiCycle() const { return false; }
@@ -128,6 +130,7 @@ protected:
   const MinMaxAll *min_max_;
   bool own_pts_;
   int priority_;
+  size_t id_;                   // Unique ID assigned by Sdc.
   ExceptionState *states_;
 };
 
diff --git a/include/sta/Sdc.hh b/include/sta/Sdc.hh
index 945093ee..7f9198ad 100644
--- a/include/sta/Sdc.hh
+++ b/include/sta/Sdc.hh
@@ -1369,6 +1369,7 @@ protected:
   InstanceSet disabled_clk_gating_checks_inst_;
   PinSet disabled_clk_gating_checks_pin_;
   ExceptionPathSet exceptions_;
+  size_t exception_id_; // Unique ID for exceptions.
 
   bool have_thru_hpin_exceptions_;
   // First pin/clock/instance/net/edge exception point to exception set map.
diff --git a/include/sta/SdcClass.hh b/include/sta/SdcClass.hh
index 8b30dca4..68f1ef14 100644
--- a/include/sta/SdcClass.hh
+++ b/include/sta/SdcClass.hh
@@ -107,12 +107,8 @@ class ExceptionState;
 class ExceptionStateLess
 {
 public:
-  ExceptionStateLess(const Network *network);
   bool operator()(const ExceptionState *state1,
                   const ExceptionState *state2) const;
-
-private:
-  const Network *network_;
 };
 
 class ExceptionPath;
diff --git a/sdc/ExceptionPath.cc b/sdc/ExceptionPath.cc
index 204a75a3..b04fb5a8 100644
--- a/sdc/ExceptionPath.cc
+++ b/sdc/ExceptionPath.cc
@@ -90,7 +90,8 @@ ExceptionPath::ExceptionPath(ExceptionFrom *from,
   to_(to),
   min_max_(min_max),
   own_pts_(own_pts),
-  priority_(priority)
+  priority_(priority),
+  id_(0)
 {
   makeStates();
 }
@@ -125,6 +126,12 @@ ExceptionPath::asString(const Network *network) const
   return result;
 }
 
+void
+ExceptionPath::setId(size_t id)
+{
+  id_ = id;
+}
+
 ExceptionPt *
 ExceptionPath::firstPt()
 {
@@ -2247,19 +2254,14 @@ ExceptionState::hash() const
   return hashSum(exception_->hash(), index_);
 }
 
-ExceptionStateLess::ExceptionStateLess(const Network *network) :
-  network_(network)
-{
-}
-
 bool
 ExceptionStateLess::operator()(const ExceptionState *state1,
                                const ExceptionState *state2) const
 {
   const ExceptionPath *except1 = state1->exception();
   const ExceptionPath *except2 = state2->exception();
-  ExceptionPathLess except_less(network_);
-  return except_less(except1, except2)
+    return except1->id() < except2->id()
+  //return except1 < except2
     || (except1 == except2
         && state1->index() < state2->index());
 }
diff --git a/sdc/Sdc.cc b/sdc/Sdc.cc
index fefbec01..7925f048 100644
--- a/sdc/Sdc.cc
+++ b/sdc/Sdc.cc
@@ -110,6 +110,7 @@ Sdc::Sdc(StaState *sta) :
   disabled_wire_edges_(network_),
   disabled_clk_gating_checks_inst_(network_),
   disabled_clk_gating_checks_pin_(network_),
+  exception_id_(0),
   have_thru_hpin_exceptions_(false),
   first_thru_edge_exceptions_(0, PinPairHash(network_), PinPairEqual()),
   path_delay_internal_startpoints_(network_),
@@ -4552,6 +4553,7 @@ void
 Sdc::recordException(ExceptionPath *exception)
 {
   exceptions_.insert(exception);
+  exception->setId(++exception_id_);
   recordMergeHashes(exception);
   recordExceptionFirstPts(exception);
   checkForThruHpins(exception);
@@ -4813,6 +4815,7 @@ void
 Sdc::deleteExceptions()
 {
   exceptions_.deleteContentsClear();
+  exception_id_ = 0;
 
   first_from_pin_exceptions_.deleteContentsClear();
   first_from_clk_exceptions_.deleteContentsClear();
@@ -5203,7 +5206,7 @@ Sdc::exceptionFromStates(const ExceptionPathSet *exceptions,
 	  // but flush all other exception states because they are lower
 	  // priority.
 	  if (states == nullptr)
-	    states = new ExceptionStateSet(network_);
+	    states = new ExceptionStateSet();
 	  states->clear();
 	  states->insert(state);
 	  // No need to examine other exceptions from this
@@ -5211,7 +5214,7 @@ Sdc::exceptionFromStates(const ExceptionPathSet *exceptions,
 	  return false;
 	}
 	if (states == nullptr)
-	  states = new ExceptionStateSet(network_);
+	  states = new ExceptionStateSet();
 	states->insert(state);
       }
     }
@@ -5258,7 +5261,7 @@ Sdc::filterRegQStates(const Pin *to_pin,
 	    && exception->matchesFirstPt(to_rf, min_max)) {
 	  ExceptionState *state = exception->firstState();
 	  if (states == nullptr)
-	    states = new ExceptionStateSet(network_);
+	    states = new ExceptionStateSet();
 	  states->insert(state);
 	}
       }
@@ -5302,7 +5305,7 @@ Sdc::exceptionThruStates(const ExceptionPathSet *exceptions,
       if (exception->matchesFirstPt(to_rf, min_max)) {
 	ExceptionState *state = exception->firstState();
 	if (states == nullptr)
-	  states = new ExceptionStateSet(network_);
+	  states = new ExceptionStateSet();
 	states->insert(state);
       }
     }
diff --git a/search/Genclks.cc b/search/Genclks.cc
index 1066df86..7d264770 100644
--- a/search/Genclks.cc
+++ b/search/Genclks.cc
@@ -703,7 +703,7 @@ Genclks::makeTag(const Clock *gclk,
   // from the get go.
   if (master_pin == gclk->srcPin())
     state = state->nextState();
-  ExceptionStateSet *states = new ExceptionStateSet(network_);
+  ExceptionStateSet *states = new ExceptionStateSet();
   states->insert(state);
   ClkInfo *clk_info = search_->findClkInfo(master_clk->edge(master_rf),
 					   master_pin, true, nullptr, true,
diff --git a/search/PathVertex.cc b/search/PathVertex.cc
index 85b0f186..799a9715 100644
--- a/search/PathVertex.cc
+++ b/search/PathVertex.cc
@@ -428,7 +428,7 @@ PrevPathVisitor::unfilteredTag(const Tag *tag) const
     ExceptionPath *except = state->exception();
     if (!except->isFilter()) {
       if (unfiltered_states == nullptr)
-	unfiltered_states = new ExceptionStateSet(network_);
+	unfiltered_states = new ExceptionStateSet();
       unfiltered_states->insert(state);
     }
   }
diff --git a/search/Search.cc b/search/Search.cc
index 350084f2..48a4956f 100644
--- a/search/Search.cc
+++ b/search/Search.cc
@@ -2563,7 +2563,7 @@ Search::mutateTag(Tag *from_tag,
       // Second pass to apply state changes and add updated existing
       // states to new states.
       if (new_states == nullptr)
-	new_states = new ExceptionStateSet(network_);
+	new_states = new ExceptionStateSet();
       for (auto state : *from_states) {
 	ExceptionPath *exception = state->exception();
 	// One edge may traverse multiple hierarchical thru pins.