diff --git a/apps/nexus/extraction.cpp b/apps/nexus/extraction.cpp
index 52f145d6..b723dba0 100644
--- a/apps/nexus/extraction.cpp
+++ b/apps/nexus/extraction.cpp
@@ -226,7 +226,7 @@ float Extraction::GetRefineError(Node *node) {
   return maxerror;
 }
 
-bool Extraction::Refine(HeapNode &hnode) {
+bool Extraction::Refine(HeapNode hnode) {
   
   Node *node = hnode.node;
   //cerr << "Refine node: " << (void *)hnode.node << " err: " << hnode.error << endl;      
@@ -287,7 +287,7 @@ bool Extraction::Refine(HeapNode &hnode) {
   return true;
 }
 
-bool Extraction::Coarse(HeapNode &hnode) {
+bool Extraction::Coarse(HeapNode hnode) {
   //cerr << "Coarse node: " << (void *)hnode.node << " err: " << hnode.error << endl;    
   Node *node = hnode.node;
   
diff --git a/apps/nexus/extraction.h b/apps/nexus/extraction.h
index b2dbcc00..a5cfa846 100644
--- a/apps/nexus/extraction.h
+++ b/apps/nexus/extraction.h
@@ -72,8 +72,8 @@ class Extraction {
   bool Expand(HeapNode &node);
   void Diff(Node *node, Cost &cost);
 
-  bool Refine(HeapNode &node);
-  bool Coarse(HeapNode &node);
+  bool Refine(HeapNode node);
+  bool Coarse(HeapNode node);
 
   void Init();
  private: