diff --git a/include/sta/Network.hh b/include/sta/Network.hh
index 879ad2c5..eab973ad 100644
--- a/include/sta/Network.hh
+++ b/include/sta/Network.hh
@@ -326,9 +326,9 @@ public:
   // Return the physical X/Y coordinates of the pin.
   virtual void location(const Pin *pin,
 			// Return values.
-			double x,
-			double y,
-			bool exists) const;
+			double &x,
+			double &y,
+			bool &exists) const;
 
   int pinCount();
   int pinCount(Instance *inst);
diff --git a/network/Network.cc b/network/Network.cc
index 535566f9..412afcfb 100644
--- a/network/Network.cc
+++ b/network/Network.cc
@@ -938,9 +938,9 @@ Network::findInstPinsMatching(const Instance *instance,
 void
 Network::location(const Pin *pin,
 		  // Return values.
-		  double x,
-		  double y,
-		  bool exists) const
+		  double &x,
+		  double &y,
+		  bool &exists) const
 {
   x = y = 0.0;
   exists = false;