diff --git a/Source/Core/VideoCommon/Src/XFMemory.h b/Source/Core/VideoCommon/Src/XFMemory.h
index 10f554072a..d36e90de39 100644
--- a/Source/Core/VideoCommon/Src/XFMemory.h
+++ b/Source/Core/VideoCommon/Src/XFMemory.h
@@ -91,8 +91,8 @@
 #define XFMEM_SETMATRIXINDA      0x1018
 #define XFMEM_SETMATRIXINDB      0x1019
 #define XFMEM_SETVIEWPORT        0x101a
-#define XFMEM_SETZSCALE          0x101c
-#define XFMEM_SETZOFFSET         0x101f
+#define XFMEM_SETCONST_ZNEAR     0x101c
+#define XFMEM_SETCONST_ZFAR      0x101f
 #define XFMEM_SETPROJECTION      0x1020
 #define XFMEM_SETNUMTEXGENS      0x103f
 #define XFMEM_SETTEXMTXINFO      0x1040
@@ -228,6 +228,7 @@ struct XFRegisters
     bool bEnableDualTexTransform;
 	float rawViewport[6];
 	float rawProjection[7];
+	float depthRangeConst[2];
 };
 
 
diff --git a/Source/Core/VideoCommon/Src/XFStructs.cpp b/Source/Core/VideoCommon/Src/XFStructs.cpp
index f058ccee01..9e7cdec9f9 100644
--- a/Source/Core/VideoCommon/Src/XFStructs.cpp
+++ b/Source/Core/VideoCommon/Src/XFStructs.cpp
@@ -171,16 +171,18 @@ void LoadXFReg(u32 transferSize, u32 baseAddress, u32 *pData)
 
 			// GXSetZScaleOffset ?
 			// Actually everything i tried didn't seem to change anything x)
-			case XFMEM_SETZSCALE:
-				// paper mario writes 16777216.0f, 1677721.75
-				// Killer 7 writes 16777216.0f here
-				WARN_LOG(VIDEO, "Set ZScale : %x=%x\n", address, data);
-				break;
+			// paper mario writes 16777216.0f, 1677721.75
+			// Killer 7 writes 16777216.0f here
+			// WARN_LOG(VIDEO, "Set ZScale : %x=%x\n", address, data);
+			// paper mario writes 16777216.0f, 5033165.0f
+			// Killer 7 alterns this between 16777216.0f and 16710107.0f
+			// WARN_LOG(VIDEO, "Set ZOffset : %x=%x\n", address, data);
 
-            case XFMEM_SETZOFFSET:
-				// paper mario writes 16777216.0f, 5033165.0f
-				// Killer 7 alterns this between 16777216.0f and 16710107.0f
-				WARN_LOG(VIDEO, "Set ZOffset : %x=%x\n", address, data);
+			case XFMEM_SETCONST_ZNEAR:
+				xfregs.depthRangeConst[0] = *((float*)&data);
+				break;
+            case XFMEM_SETCONST_ZFAR:
+				xfregs.depthRangeConst[1] = *((float*)&data);
 				break;
 
 			// --------------
diff --git a/Source/Plugins/Plugin_VideoOGL/Src/Render.cpp b/Source/Plugins/Plugin_VideoOGL/Src/Render.cpp
index bb745d5bfd..580ea83cdd 100644
--- a/Source/Plugins/Plugin_VideoOGL/Src/Render.cpp
+++ b/Source/Plugins/Plugin_VideoOGL/Src/Render.cpp
@@ -181,6 +181,8 @@ void HandleCgError(CGcontext ctx, CGerror err, void* appdata)
 // Init functions
 bool Renderer::Init()
 {
+	xfregs.depthRangeConst[0] = 16777216.0f;
+	xfregs.depthRangeConst[1] = 16777216.0f;
     bool bSuccess = true;
 	s_blendMode = 0;
 	s_MSAACoverageSamples = 0;
@@ -1446,14 +1448,11 @@ void UpdateViewport()
 	int GLy = (int)ceil(Renderer::GetTargetHeight() - ((int)(xfregs.rawViewport[4] - xfregs.rawViewport[1] - 342 - scissorYOff)) * MValueY);
 	int GLWidth = (int)ceil(abs((int)(2 * xfregs.rawViewport[0])) * MValueX);
 	int GLHeight = (int)ceil(abs((int)(2 * xfregs.rawViewport[1])) * MValueY);
+	double GLNear = (xfregs.rawViewport[5] - xfregs.rawViewport[2]) / xfregs.depthRangeConst[0];
+	double GLFar = xfregs.rawViewport[5] / xfregs.depthRangeConst[1];
 
 	// Update the view port
 	glViewport(GLx, GLy, GLWidth, GLHeight);
-
-	// GLDepthRange - this could be a source of trouble - see the viewport hacks.
-	// TODO : Should this use 16777216.0f or 16777215.0f ? 
-	double GLNear = (xfregs.rawViewport[5] - xfregs.rawViewport[2]) / 16777215.0f;
-	double GLFar = xfregs.rawViewport[5] / 16777215.0f;
 	glDepthRange(GLNear, GLFar);
 
 	// -------------------------------------