diff --git a/apps/nexus/nexus.cpp b/apps/nexus/nexus.cpp
index 80abd8ad..590f17e3 100644
--- a/apps/nexus/nexus.cpp
+++ b/apps/nexus/nexus.cpp
@@ -111,14 +111,14 @@ unsigned int Nexus::AddPatch(unsigned int nvert, unsigned int nface,
   return index.size() -1;
 }
 
-void Nexus::Join(std::vector<unsigned int> &patches,
+void Nexus::Join(const std::vector<unsigned int> &patches,
 		 std::vector<Point3f> &newvert,
 		 std::vector<unsigned int> &newface,
 		 std::vector<Link> &newbord) {
 
   map<unsigned int, vector<unsigned int> > remap;
 
-  vector<unsigned int>::iterator i;
+  vector<unsigned int>::const_iterator i;
   for(i = patches.begin(); i != patches.end(); i++) {
     unsigned int patch = *i;
     Nexus::Entry &entry = index[patch];
diff --git a/apps/nexus/nexus.h b/apps/nexus/nexus.h
index 9109af8a..7a1a9c26 100644
--- a/apps/nexus/nexus.h
+++ b/apps/nexus/nexus.h
@@ -44,7 +44,7 @@ class Nexus {
 			unsigned int nbord);
 
   //  unsigned int Join(std::vector<unsigned int> &patches);
-  void Join(std::vector<unsigned int> &patches,
+  void Join(const std::vector<unsigned int> &patches,
 	    std::vector<vcg::Point3f> &vert,
 	    std::vector<unsigned int> &faces,
 	    std::vector<Link> &links);