diff --git a/include/sta/Sta.hh b/include/sta/Sta.hh
index 0d63c334..cbb91c82 100644
--- a/include/sta/Sta.hh
+++ b/include/sta/Sta.hh
@@ -458,36 +458,36 @@ public:
   void setCaseAnalysis(Pin *pin,
 		       LogicValue value);
   void removeCaseAnalysis(Pin *pin);
-  void setInputDelay(Pin *pin,
+  void setInputDelay(const Pin *pin,
 		     const RiseFallBoth *rf,
-		     Clock *clk,
+		     const Clock *clk,
 		     const RiseFall *clk_rf,
-		     Pin *ref_pin,
+		     const Pin *ref_pin,
 		     bool source_latency_included,
 		     bool network_latency_included,
 		     const MinMaxAll *min_max,
 		     bool add,
 		     float delay);
-  void removeInputDelay(Pin *pin,
-			RiseFallBoth *rf, 
-			Clock *clk,
-			RiseFall *clk_rf, 
-			MinMaxAll *min_max);
-  void setOutputDelay(Pin *pin,
+  void removeInputDelay(const Pin *pin,
+			const RiseFallBoth *rf, 
+			const Clock *clk,
+			const RiseFall *clk_rf, 
+			const MinMaxAll *min_max);
+  void setOutputDelay(const Pin *pin,
 		      const RiseFallBoth *rf,
-		      Clock *clk,
+		      const Clock *clk,
 		      const RiseFall *clk_rf,
-		      Pin *ref_pin,
+		      const Pin *ref_pin,
 		      bool source_latency_included,
 		      bool network_latency_included,
 		      const MinMaxAll *min_max,
 		      bool add,
 		      float delay);
-  void removeOutputDelay(Pin *pin,
-			 RiseFallBoth *rf, 
-			 Clock *clk,
-			 RiseFall *clk_rf, 
-			 MinMaxAll *min_max);
+  void removeOutputDelay(const Pin *pin,
+			 const RiseFallBoth *rf, 
+			 const Clock *clk,
+			 const RiseFall *clk_rf, 
+			 const MinMaxAll *min_max);
   void makeFalsePath(ExceptionFrom *from,
 		     ExceptionThruSeq *thrus,
 		     ExceptionTo *to,
diff --git a/search/Sta.cc b/search/Sta.cc
index 8c8a8374..ad3f42be 100644
--- a/search/Sta.cc
+++ b/search/Sta.cc
@@ -1858,11 +1858,11 @@ Sta::removeCaseAnalysis(Pin *pin)
 }
 
 void
-Sta::setInputDelay(Pin *pin,
+Sta::setInputDelay(const Pin *pin,
 		   const RiseFallBoth *rf,
-		   Clock *clk,
+		   const Clock *clk,
 		   const RiseFall *clk_rf,
-		   Pin *ref_pin,
+		   const Pin *ref_pin,
 		   bool source_latency_included,
 		   bool network_latency_included,
 		   const MinMaxAll *min_max,
@@ -1877,22 +1877,22 @@ Sta::setInputDelay(Pin *pin,
 }
 
 void 
-Sta::removeInputDelay(Pin *pin,
-		      RiseFallBoth *rf,
-		      Clock *clk,
-		      RiseFall *clk_rf, 
-		      MinMaxAll *min_max)
+Sta::removeInputDelay(const Pin *pin,
+		      const RiseFallBoth *rf,
+		      const Clock *clk,
+		      const RiseFall *clk_rf,
+		      const MinMaxAll *min_max)
 {
   sdc_->removeInputDelay(pin, rf, clk, clk_rf, min_max);
   search_->arrivalInvalid(pin);
 }
 
 void
-Sta::setOutputDelay(Pin *pin,
+Sta::setOutputDelay(const Pin *pin,
 		    const RiseFallBoth *rf,
-		    Clock *clk,
+		    const Clock *clk,
 		    const RiseFall *clk_rf,
-		    Pin *ref_pin,
+		    const Pin *ref_pin,
 		    bool source_latency_included,
 		    bool network_latency_included,
 		    const MinMaxAll *min_max,
@@ -1907,11 +1907,11 @@ Sta::setOutputDelay(Pin *pin,
 }
 
 void 
-Sta::removeOutputDelay(Pin *pin,
-		       RiseFallBoth *rf, 
-		       Clock *clk,
-		       RiseFall *clk_rf, 
-		       MinMaxAll *min_max)
+Sta::removeOutputDelay(const Pin *pin,
+		       const RiseFallBoth *rf,
+		       const Clock *clk,
+		       const RiseFall *clk_rf,
+		       const MinMaxAll *min_max)
 {
   sdc_->removeOutputDelay(pin, rf, clk, clk_rf, min_max);
   sdcChangedGraph();