diff --git a/include/sta/Sta.hh b/include/sta/Sta.hh
index c0522dfb..b67cca46 100644
--- a/include/sta/Sta.hh
+++ b/include/sta/Sta.hh
@@ -1052,6 +1052,9 @@ public:
   // Propagate liberty constant functions and pins tied high/low through
   // combinational logic and registers.
   void findLogicConstants();
+  // Clear the constants found by findLogicConstants so they do not interfere
+  // with normal constant propagate for timing.
+  void clearLogicConstants();
 
   // Iterator for instances sorted by max driver pin slew.
   // Caller owns iterator and iterator->container().
diff --git a/search/Sim.cc b/search/Sim.cc
index dc19e8a0..52147c2c 100644
--- a/search/Sim.cc
+++ b/search/Sim.cc
@@ -569,6 +569,7 @@ Sim::findLogicConstants()
   enqueueConstantPinInputs();
   setConstFuncPins();
   propagateConstants(true);
+  valid_ = true;
 }
 
 void
diff --git a/search/Sta.cc b/search/Sta.cc
index f2fc200e..3a53274e 100644
--- a/search/Sta.cc
+++ b/search/Sta.cc
@@ -3447,9 +3447,16 @@ Sta::simLogicValue(const Pin *pin)
 void
 Sta::findLogicConstants()
 {
+  ensureGraph();
   sim_->findLogicConstants();
 }
 
+void
+Sta::clearLogicConstants()
+{
+  sim_->clear();
+}
+
 void
 Sta::setPortExtPinCap(Port *port,
 		      const RiseFallBoth *rf,