diff --git a/sources/reactphysics3d/physics/Kilogram.cpp b/sources/reactphysics3d/physics/Kilogram.cpp
deleted file mode 100644
index efce5863..00000000
--- a/sources/reactphysics3d/physics/Kilogram.cpp
+++ /dev/null
@@ -1,51 +0,0 @@
-/****************************************************************************
- * Copyright (C) 2009      Daniel Chappuis                                  *
- ****************************************************************************
- * This file is part of ReactPhysics3D.                                     *
- *                                                                          *
- * ReactPhysics3D is free software: you can redistribute it and/or modify   *
- * it under the terms of the GNU Lesser General Public License as published *
- * by the Free Software Foundation, either version 3 of the License, or     *
- * (at your option) any later version.                                      *
- *                                                                          *
- * ReactPhysics3D is distributed in the hope that it will be useful,        *
- * but WITHOUT ANY WARRANTY; without even the implied warranty of           *
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the             *
- * GNU Lesser General Public License for more details.                      *
- *                                                                          *
- * You should have received a copy of the GNU Lesser General Public License *
- * along with ReactPhysics3D. If not, see <http://www.gnu.org/licenses/>.   *
- ***************************************************************************/
-
-// Libraries
-#include "Kilogram.h"
-
-// We want to use the ReactPhysics3D namespace
-using namespace reactphysics3d;
-
-// Constructor
-Kilogram::Kilogram() {
-    value = 0.0;
-}
-
-// Constructor with arguments
-Kilogram::Kilogram(double value) throw(std::invalid_argument) {
-    // Check if the value is positive
-    if (value >= 0) {
-        this->value = value;
-    }
-    else {
-        // We throw an exception
-        throw std::invalid_argument("Exception in Kilogram : Wrong argument, a mass value has to be positive");
-    }
- }
-
- // Copy-constructor
- Kilogram::Kilogram(const Kilogram& mass) {
-    this->value = mass.value;
- }
-
- // Destructor
- Kilogram::~Kilogram() {
-
- }
diff --git a/sources/reactphysics3d/physics/Kilogram.h b/sources/reactphysics3d/physics/Kilogram.h
deleted file mode 100644
index c9fa5622..00000000
--- a/sources/reactphysics3d/physics/Kilogram.h
+++ /dev/null
@@ -1,73 +0,0 @@
-/****************************************************************************
- * Copyright (C) 2009      Daniel Chappuis                                  *
- ****************************************************************************
- * This file is part of ReactPhysics3D.                                     *
- *                                                                          *
- * ReactPhysics3D is free software: you can redistribute it and/or modify   *
- * it under the terms of the GNU Lesser General Public License as published *
- * by the Free Software Foundation, either version 3 of the License, or     *
- * (at your option) any later version.                                      *
- *                                                                          *
- * ReactPhysics3D is distributed in the hope that it will be useful,        *
- * but WITHOUT ANY WARRANTY; without even the implied warranty of           *
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the             *
- * GNU Lesser General Public License for more details.                      *
- *                                                                          *
- * You should have received a copy of the GNU Lesser General Public License *
- * along with ReactPhysics3D. If not, see <http://www.gnu.org/licenses/>.   *
- ***************************************************************************/
-
- #ifndef KILOGRAM_H
- #define KILOGRAM_H
-
- // Libraries
- #include <stdexcept>
-
- // TODO : Remove the kilogram class
-
- // Namespace ReactPhysics3D
- namespace reactphysics3d {
-
-/*  -------------------------------------------------------------------
-    Class Kilogram :
-        The Kilogram class represents a mass unity. The value inside is a
-        mass in kilogram.
-    -------------------------------------------------------------------
-*/
-class Kilogram {
-    private :
-        double value;                           // Mass value in kilogram
-
-    public :
-        Kilogram();                                                 // Constructor
-        Kilogram(double value) throw(std::invalid_argument);        // Constructor with arguments
-        Kilogram(const Kilogram& mass);                             // Copy-constructor
-        virtual ~Kilogram();                                        // Destructor
-
-        double getValue() const;                                    // Return the mass value in kilogram
-        void setValue(double value) throw(std::invalid_argument);   // Set the mass value
-};
-
-// --- Inlines functions --- //
-
-// Return the value in kilogram
-inline double Kilogram::getValue() const {
-    return value;
-}
-
-// Set the value in kilogram
-inline void Kilogram::setValue(double value) throw(std::invalid_argument) {
-
-    // Check if the time value is positive
-    if (value >= 0) {
-        this->value = value;
-    }
-    else {
-        // We throw an exception
-        throw std::invalid_argument("Exception in Time: Wrong argument, a time value has to be positive");
-    }
-}
-
-}
-
- #endif
diff --git a/sources/reactphysics3d/physics/Time.h b/sources/reactphysics3d/physics/Time.h
index c79462dc..c7b5a962 100644
--- a/sources/reactphysics3d/physics/Time.h
+++ b/sources/reactphysics3d/physics/Time.h
@@ -35,7 +35,7 @@
 */
 class Time {
     private :
-        double value;                   // Time in seconds
+        long double value;                   // Time in seconds
 
     public :
         Time();                                                         // Constructor
@@ -108,7 +108,6 @@ inline Time Time::operator*(double number) const throw(std::invalid_argument) {
 }
 
 // Overloaded operator for less than comparison
-// TODO : TEST THIS METHOD
 inline bool Time::operator<(const Time& time2) const {
     return (getValue() < time2.getValue());
 }
@@ -119,7 +118,6 @@ inline bool Time::operator<=(const Time& time2) const {
 }
 
 // Overloaded operator for greater than comparison
-// TODO : TEST THIS METHOD
 inline bool Time::operator>(const Time& time2) const {
     return (getValue() > time2.getValue());
 }
diff --git a/sources/reactphysics3d/physics/physics.h b/sources/reactphysics3d/physics/physics.h
index eb60ed7b..ce339c67 100644
--- a/sources/reactphysics3d/physics/physics.h
+++ b/sources/reactphysics3d/physics/physics.h
@@ -22,6 +22,5 @@
 
 // Libraries
 #include "Time.h"
-#include "Kilogram.h"
 
 #endif