diff --git a/Core/Ppu.cpp b/Core/Ppu.cpp
index 554f7e3..32fa9fb 100644
--- a/Core/Ppu.cpp
+++ b/Core/Ppu.cpp
@@ -183,7 +183,7 @@ void Ppu::Write(uint32_t addr, uint8_t value)
 			//VMDATAL - VRAM Data Write low byte
 			_vram[_vramAddress << 1] = value;
 			if(!_vramAddrIncrementOnSecondReg) {
-				_vramAddress += _vramIncrementValue;
+				_vramAddress = (_vramIncrementValue + _vramIncrementValue) & 0x7FFF;
 			}
 			break;
 
@@ -191,7 +191,7 @@ void Ppu::Write(uint32_t addr, uint8_t value)
 			//VMDATAH - VRAM Data Write high byte
 			_vram[(_vramAddress << 1) + 1] = value;
 			if(_vramAddrIncrementOnSecondReg) {
-				_vramAddress += _vramIncrementValue;
+				_vramAddress = (_vramIncrementValue + _vramIncrementValue) & 0x7FFF;
 			}
 			break;
 
@@ -203,7 +203,7 @@ void Ppu::Write(uint32_t addr, uint8_t value)
 		case 0x2122: 
 			//CGRAM Data write (CGDATA)
 			_cgram[_cgramAddress] = value;
-			_cgramAddress++;
+			_cgramAddress = (_cgramAddress + 1) & (Ppu::CgRamSize - 1);
 			break;
 
 		case 0x4200: