diff --git a/owlps-positioning/src/stock.cc b/owlps-positioning/src/stock.cc
index dee9a44..51a15bf 100644
--- a/owlps-positioning/src/stock.cc
+++ b/owlps-positioning/src/stock.cc
@@ -148,6 +148,21 @@ const Mobile& Stock::find_create_mobile(const string &mac)
 }
 
 
+/**
+ * If the Mobile already exists, it is replaced by the \em source.
+ */
+const Mobile& Stock::find_create_mobile(const Mobile &source)
+{
+  const string &mac = source.get_mac_addr() ;
+  unordered_map<string, Mobile>::const_iterator i = mobiles.find(mac) ;
+  if (i != mobiles.end())
+    return i->second ;
+
+  mobiles[mac] = source ;
+  return mobiles[mac] ;
+}
+
+
 
 /* *** AccessPoint operations *** */
 
diff --git a/owlps-positioning/src/stock.hh b/owlps-positioning/src/stock.hh
index ab4cbab..db58fd3 100644
--- a/owlps-positioning/src/stock.hh
+++ b/owlps-positioning/src/stock.hh
@@ -70,8 +70,11 @@ public:
   //@{
   /// Reads the Mobile corresponding to a given MAC address
   static const Mobile& get_mobile(const std::string &mac) ;
-  /// Searches for a Mobile and creates it if it does not exist
+  /// \brief Searches for a Mobile given its MAC address and creates
+  /// it if it does not exist
   static const Mobile& find_create_mobile(const std::string &mac) ;
+  /// Searches for a Mobile and create it if it does not exist
+  static const Mobile& find_create_mobile(const Mobile &source) ;
   /// \brief Returns a reference to the Mobile corresponding to a
   /// given MAC address
   static Mobile& getw_mobile(const std::string &mac) ;