diff --git a/lib/Analysis/DataStructure/DataStructure.cpp b/lib/Analysis/DataStructure/DataStructure.cpp
index ecfed8d..3a55c54 100644
--- a/lib/Analysis/DataStructure/DataStructure.cpp
+++ b/lib/Analysis/DataStructure/DataStructure.cpp
@@ -394,8 +394,8 @@
 void DSGraph::dump() const { print(std::cerr); }
 
 
-DSNodeHandle copyHelper(const DSNodeHandle* fromNode,
-                        std::map<const DSNode*, DSNode*> *NodeMap) {
+static DSNodeHandle copyHelper(const DSNodeHandle* fromNode,
+                               std::map<const DSNode*, DSNode*> *NodeMap) {
   return DSNodeHandle((*NodeMap)[fromNode->getNode()], fromNode->getOffset());
 }