diff --git a/BBGE/Slider.h b/BBGE/Slider.h
index d5c2b90..d415e0f 100644
--- a/BBGE/Slider.h
+++ b/BBGE/Slider.h
@@ -18,6 +18,10 @@ You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
+
+#ifndef __BBGE_SLIDER__
+#define __BBGE_SLIDER__
+
 #include "Quad.h"
 
 class Slider : public RenderObject
@@ -54,3 +58,4 @@ protected:
 	void onUpdate(float dt);
 };
 
+#endif