diff --git a/source/Irrlicht/CIrrDeviceSDL.cpp b/source/Irrlicht/CIrrDeviceSDL.cpp
index 0a0f371..d0a21cd 100644
--- a/source/Irrlicht/CIrrDeviceSDL.cpp
+++ b/source/Irrlicht/CIrrDeviceSDL.cpp
@@ -335,7 +335,7 @@ bool CIrrDeviceSDL::run()
 				else
 				{
 					irrevent.MouseInput.Event = irr::EMIE_RMOUSE_LEFT_UP;
-					MouseButtonStates &= !irr::EMBSM_RIGHT;
+					MouseButtonStates &= ~irr::EMBSM_RIGHT;
 				}
 				break;
 
@@ -348,7 +348,7 @@ bool CIrrDeviceSDL::run()
 				else
 				{
 					irrevent.MouseInput.Event = irr::EMIE_MMOUSE_LEFT_UP;
-					MouseButtonStates &= !irr::EMBSM_MIDDLE;
+					MouseButtonStates &= ~irr::EMBSM_MIDDLE;
 				}
 				break;