diff --git a/source/Platform/Unix/X11Mouse.cpp b/source/Platform/Unix/X11Mouse.cpp
index cabbedc..f4bd651 100644
--- a/source/Platform/Unix/X11Mouse.cpp
+++ b/source/Platform/Unix/X11Mouse.cpp
@@ -5,8 +5,17 @@
 #include "X11Display.h"
 #include "X11Mouse.h"
 
+#define XBUTTON1BIT (1<<0)
+#define XBUTTON2BIT (1<<1)
+
 namespace sp {
 
+namespace _priv {
+
+	// Variable to handle extra button state (not queryable in xlib)
+	unsigned int xstate = 0;
+}
+
 X11Mouse::X11Mouse() :
 m_btn_state(0)
 {
@@ -35,8 +44,6 @@ bool X11Mouse::isButtonDown(Mouse::Button button) const
 		return false;
 	}
 
-	// TODO: Button1 and 2 is defined in x11 and
-	// therefore clashes with Mouse::Button::Button1 and 2.
 	switch(button) {
 	case Mouse::Button::Left :
 		return m_btn_state & Button1Mask;
@@ -44,6 +51,10 @@ bool X11Mouse::isButtonDown(Mouse::Button button) const
 		return m_btn_state & Button3Mask;
     case Mouse::Button::Middle :
 		return m_btn_state & Button2Mask;
+	case Mouse::Button::XButton1 :
+		return _priv::xstate & XBUTTON1BIT;
+	case Mouse::Button::XButton2 :
+		return _priv::xstate & XBUTTON2BIT;
 	default :
 		return false;
 	}
@@ -82,6 +93,11 @@ void X11Mouse::updateFocusedWindow()
 	m_win = focus ? (::Window) focus->getHandle() : 0;
 }
 
+#define SETXSTATE(bit) \
+	_priv::xstate = (xevent->type == ButtonPress) \
+		? _priv::xstate | (bit) \
+		: _priv::xstate & ~(bit)
+
 bool X11Mouse::handleMessage(XEvent* xevent, Event& event)
 {
 	if (xevent->type == MotionNotify) {
@@ -99,9 +115,10 @@ bool X11Mouse::handleMessage(XEvent* xevent, Event& event)
 		case Button1 : trans = Mouse::Button::Left; break;
 		case Button2 : trans = Mouse::Button::Middle; break;
 		case Button3 : trans = Mouse::Button::Right; break;
-		// TODO: name clash, need to rename Mouse::Button enums.
-		// case Button4 : trans = Mouse::Button::Button1; break; // clashes with X11's "Button1" define.
-		// case Button5 : trans = Mouse::Button::Button2; break; // clashes with X11's "Button2" define.
+		// Xlib do not support querying of button 8 and 9.
+		// so we have to fake it.
+		case 8 : trans = Mouse::Button::XButton1; SETXSTATE(XBUTTON1BIT); break;
+		case 9 : trans = Mouse::Button::XButton2; SETXSTATE(XBUTTON2BIT); break;
 		}
 
 		if (trans != Mouse::Button::Unknown) {