diff --git a/include/triton/ir/value.h b/include/triton/ir/value.h
index e192a54ef..e1599d6bc 100644
--- a/include/triton/ir/value.h
+++ b/include/triton/ir/value.h
@@ -20,15 +20,18 @@ class visitor;
 //===----------------------------------------------------------------------===//
 
 class value {
+public:
+  typedef std::set<user*> users_t;
+
 public:
   // constructor
   value(type *ty, const std::string &name = "");
   virtual ~value(){ }
   // uses
   void add_use(user* arg);
-  unsigned erase_use(user* arg);
+  users_t::iterator erase_use(user* arg);
   const std::set<user*> &get_users() { return users_; }
-  virtual void replace_all_uses_with(value *target);
+  void replace_all_uses_with(value *target);
   // name
   void set_name(const std::string &name);
   const std::string &get_name() const { return name_; }
@@ -41,7 +44,7 @@ private:
 
 protected:
   type *ty_;
-  std::set<user*> users_;
+  users_t users_;
 };
 
 //===----------------------------------------------------------------------===//
@@ -63,6 +66,7 @@ public:
   user(type *ty, unsigned num_ops, const std::string &name = "")
       : value(ty, name), ops_(num_ops), num_ops_(num_ops), num_hidden_(0){
   }
+  virtual ~user() { }
 
   // Operands
   const ops_t& ops() { return ops_; }
@@ -74,8 +78,7 @@ public:
   unsigned get_num_hidden() const;
 
   // Utils
-  void replace_all_uses_with(value *target);
-  void replace_uses_of_with(value *before, value *after);
+  value::users_t::iterator replace_uses_of_with(value *before, value *after);
 
 
 private:
diff --git a/lib/ir/module.cc b/lib/ir/module.cc
index 67617478b..28edb4e4f 100644
--- a/lib/ir/module.cc
+++ b/lib/ir/module.cc
@@ -71,9 +71,9 @@ ir::value *module::try_remove_trivial_phis(ir::phi_node *&phi){
   // unique value or self-reference
   ir::value *same = *non_self_ref.begin();
   assert(same != nullptr);
-  std::set<ir::user*> users = phi->get_users();
   phi->replace_all_uses_with(same);
   phi->erase_from_parent();
+  std::set<ir::user*> users = phi->get_users();
   for(ir::user* u: users)
   if(auto *uphi = dynamic_cast<ir::phi_node*>(u))
     if(uphi != phi)
diff --git a/lib/ir/value.cc b/lib/ir/value.cc
index a43aaa05e..81f803df6 100644
--- a/lib/ir/value.cc
+++ b/lib/ir/value.cc
@@ -1,4 +1,5 @@
 #include <cassert>
+#include <iostream>
 #include "triton/ir/value.h"
 #include "triton/ir/instructions.h"
 
@@ -19,8 +20,11 @@ void value::add_use(user *arg) {
   users_.insert(arg);
 }
 
-unsigned value::erase_use(user *arg){
-  return users_.erase(arg);
+value::users_t::iterator value::erase_use(user *arg){
+  auto it = users_.find(arg);
+  if(it == users_.end())
+    return it;
+  return users_.erase(it);
 }
 
 // TODO: automatic naming scheme + update symbol table
@@ -29,9 +33,12 @@ void value::set_name(const std::string &name){
 }
 
 void value::replace_all_uses_with(value *target){
-  throw std::runtime_error("not implemented");
+  for (auto it = users_.begin(); it != users_.end(); ) {
+    it = (*it)->replace_uses_of_with(this, target);
+  }
 }
 
+
 void visitor::visit_value(ir::value* v) {
   v->accept(this);
 }
@@ -59,18 +66,12 @@ unsigned user::get_num_hidden() const {
   return num_hidden_;
 }
 
-void user::replace_all_uses_with(value *target) {
-  for(auto it = users_.begin(); it != users_.end(); it++){
-    (*it)->replace_uses_of_with(this, target);
-  }
-}
-
-void user::replace_uses_of_with(value *before, value *after) {
+value::users_t::iterator user::replace_uses_of_with(value *before, value *after) {
   for(size_t i = 0; i < ops_.size(); i++)
     if(ops_[i] == before)
       ops_[i] = after;
   after->add_use(this);
-  before->erase_use(this);
+  return before->erase_use(this);
 }
 
 
diff --git a/python/setup.py b/python/setup.py
index d867dc122..cb6b1bcd6 100644
--- a/python/setup.py
+++ b/python/setup.py
@@ -100,7 +100,7 @@ for d in directories:
 
 setup(
     name='triton',
-    version='0.1',
+    version='0.1.1',
     author='Philippe Tillet',
     author_email='ptillet@g.harvard.edu',
     description='A language and compiler for custom Deep Learning operations',