diff --git a/src/mobility/mobility-model.cc b/src/mobility/mobility-model.cc
index 959e29a1e..808c5f4dd 100644
--- a/src/mobility/mobility-model.cc
+++ b/src/mobility/mobility-model.cc
@@ -52,9 +52,9 @@ MobilityModel::Set (const Position &position)
 }
 
 double 
-MobilityModel::GetDistanceFrom (const MobilityModel &other) const
+MobilityModel::GetDistanceFrom (Ptr<const MobilityModel> other) const
 {
-  Position oPosition = other.DoGet ();
+  Position oPosition = other->DoGet ();
   Position position = DoGet ();
   return CalculateDistance (position, oPosition);
 }
diff --git a/src/mobility/mobility-model.h b/src/mobility/mobility-model.h
index 4c4cf9000..5d0e6ee4a 100644
--- a/src/mobility/mobility-model.h
+++ b/src/mobility/mobility-model.h
@@ -57,7 +57,7 @@ public:
    * \param position a reference to another mobility model
    * \returns the distance between the two objects. Unit is meters.
    */
-  double GetDistanceFrom (const MobilityModel &position) const;
+  double GetDistanceFrom (Ptr<const MobilityModel> position) const;
 protected:
   /**
    * Must be invoked by subclasses when the course of the