diff --git a/Core/Ppu.cpp b/Core/Ppu.cpp
index 43312ed..a800900 100644
--- a/Core/Ppu.cpp
+++ b/Core/Ppu.cpp
@@ -564,10 +564,57 @@ void Ppu::ApplyColorMath()
 		return;
 	}
 
+	uint8_t activeWindowCount = (uint8_t)_window[0].ActiveLayers[Ppu::ColorWindowIndex] + (uint8_t)_window[1].ActiveLayers[Ppu::ColorWindowIndex];
+
 	for(int x = 0; x < 256; x++) {
 		if(_rowPixelFlags[x] & PixelFlags::AllowColorMath) {
-			uint16_t otherPixel;
 			uint8_t halfShift = _colorMathHalveResult ? 1 : 0;
+			uint16_t &mainPixel = _currentBuffer[(_scanline << 8) | x];
+
+			bool isInsideWindow = activeWindowCount && ProcessMaskWindow<Ppu::ColorWindowIndex>(activeWindowCount, x);
+			//Set color to black as needed based on clip mode
+			switch(_colorMathClipMode) {
+				default:
+				case ColorWindowMode::Never: break;
+
+				case ColorWindowMode::OutsideWindow: 
+					if(!isInsideWindow) {
+						mainPixel = 0;
+						halfShift = 0;
+					}
+					break;
+
+				case ColorWindowMode::InsideWindow:
+					if(isInsideWindow) {
+						mainPixel = 0;
+						halfShift = 0;
+					}
+					break;
+
+				case ColorWindowMode::Always: mainPixel = 0; break;
+			}
+
+			//Prevent color math as needed based on mode
+			switch(_colorMathPreventMode) {
+				default:
+				case ColorWindowMode::Never: break;
+
+				case ColorWindowMode::OutsideWindow:
+					if(!isInsideWindow) {
+						continue;
+					}
+					break;
+
+				case ColorWindowMode::InsideWindow:
+					if(isInsideWindow) {
+						continue;
+					}
+					break;
+
+				case ColorWindowMode::Always: continue;
+			}
+
+			uint16_t otherPixel;
 			if(_colorMathAddSubscreen) {
 				if(_subScreenFilled[x]) {
 					otherPixel = _subScreenBuffer[x];
@@ -580,7 +627,6 @@ void Ppu::ApplyColorMath()
 				otherPixel = _fixedColor;
 			}
 
-			uint16_t &mainPixel = _currentBuffer[(_scanline << 8) | x];
 
 			if(_colorMathSubstractMode) {
 				uint16_t r = std::max((mainPixel & 0x001F) - (otherPixel & 0x001F), 0) >> halfShift;
@@ -1014,8 +1060,8 @@ void Ppu::Write(uint32_t addr, uint8_t value)
 		
 		case 0x2130:
 			//CGWSEL - Color Addition Select
-			_colorMathClipMode = (value >> 6) & 0x03; //TODO
-			_colorMathPreventMode = (value >> 4) & 0x03; //TODO
+			_colorMathClipMode = (ColorWindowMode)((value >> 6) & 0x03);
+			_colorMathPreventMode = (ColorWindowMode)((value >> 4) & 0x03);
 			_colorMathAddSubscreen = (value & 0x02) != 0;
 			_directColorMode = (value & 0x01) != 0; //TODO
 			break;
diff --git a/Core/Ppu.h b/Core/Ppu.h
index cde284b..e6dab3b 100644
--- a/Core/Ppu.h
+++ b/Core/Ppu.h
@@ -28,6 +28,7 @@ public:
 
 private:
 	constexpr static int SpriteLayerIndex = 4;
+	constexpr static int ColorWindowIndex = 5;
 
 	constexpr static const uint8_t _oamSizes[8][2][2] = {
 		{ { 1, 1 }, { 2, 2 } }, //8x8 + 16x16
@@ -110,8 +111,8 @@ private:
 
 	bool _directColorMode = false;
 
-	uint8_t _colorMathClipMode = 0;
-	uint8_t _colorMathPreventMode = 0;
+	ColorWindowMode _colorMathClipMode = ColorWindowMode::Never;
+	ColorWindowMode _colorMathPreventMode = ColorWindowMode::Never;
 	bool _colorMathAddSubscreen = false;
 	uint8_t _colorMathEnabled = 0;
 	bool _colorMathSubstractMode = false;
diff --git a/Core/PpuTypes.h b/Core/PpuTypes.h
index f81ff6a..4d9f7b3 100644
--- a/Core/PpuTypes.h
+++ b/Core/PpuTypes.h
@@ -54,4 +54,12 @@ enum class  WindowMaskLogic
 	And = 1,
 	Xor = 2,
 	Xnor = 3
-};
\ No newline at end of file
+};
+
+enum class ColorWindowMode
+{
+	Never = 0,
+	OutsideWindow = 1,
+	InsideWindow = 2,
+	Always = 3
+};