diff --git a/Source/Core/VideoBackends/D3D/Src/Render.cpp b/Source/Core/VideoBackends/D3D/Src/Render.cpp
index d58cc59e98..7f9218de11 100644
--- a/Source/Core/VideoBackends/D3D/Src/Render.cpp
+++ b/Source/Core/VideoBackends/D3D/Src/Render.cpp
@@ -513,50 +513,38 @@ void Renderer::UpdateViewport(Matrix44& vpCorrection)
 	int scissorXOff = bpmem.scissorOffset.x * 2;
 	int scissorYOff = bpmem.scissorOffset.y * 2;
 
-	// TODO: ceil, floor or just cast to int?
-	// TODO: Directly use the floats instead of rounding them?
-	int intendedX = Renderer::EFBToScaledX((int)ceil(xfregs.viewport.xOrig - xfregs.viewport.wd - scissorXOff));
-	int intendedY = Renderer::EFBToScaledY((int)ceil(xfregs.viewport.yOrig + xfregs.viewport.ht - scissorYOff));
-	int intendedWd = Renderer::EFBToScaledX((int)ceil(2.0f * xfregs.viewport.wd));
-	int intendedHt = Renderer::EFBToScaledY((int)ceil(-2.0f * xfregs.viewport.ht));
-	if (intendedWd < 0)
+	float intendedX = Renderer::EFBToScaledXf(xfregs.viewport.xOrig - xfregs.viewport.wd - scissorXOff);
+	float intendedY = Renderer::EFBToScaledYf(xfregs.viewport.yOrig + xfregs.viewport.ht - scissorYOff);
+	float intendedWd = Renderer::EFBToScaledXf(2.0f * xfregs.viewport.wd);
+	float intendedHt = Renderer::EFBToScaledYf(-2.0f * xfregs.viewport.ht);
+	if (intendedWd < 0.f)
 	{
 		intendedX += intendedWd;
 		intendedWd = -intendedWd;
 	}
-	if (intendedHt < 0)
+	if (intendedHt < 0.f)
 	{
 		intendedY += intendedHt;
 		intendedHt = -intendedHt;
 	}
 
 	// In D3D, the viewport rectangle must fit within the render target.
-	int X = intendedX;
-	if (X < 0)
-		X = 0;
+	float X = (intendedX >= 0.f) ? intendedX : 0.f;
+	float Y = (intendedY >= 0.f) ? intendedY : 0.f;
+	float Wd = (X + intendedWd <= GetTargetWidth()) ? intendedWd : (GetTargetWidth() - X);
+	float Ht = (Y + intendedHt <= GetTargetHeight()) ? intendedHt : (GetTargetHeight() - Y);
 
-	int Y = intendedY;
-	if (Y < 0)
-		Y = 0;
-
-	int Wd = intendedWd;
-	if (X + Wd > GetTargetWidth())
-		Wd = GetTargetWidth() - X;
-	int Ht = intendedHt;
-	if (Y + Ht > GetTargetHeight())
-		Ht = GetTargetHeight() - Y;
-	
 	// If GX viewport is off the render target, we must clamp our viewport
 	// within the bounds. Use the correction matrix to compensate.
 	ViewportCorrectionMatrix(vpCorrection,
-		(float)intendedX, (float)intendedY,
-		(float)intendedWd, (float)intendedHt,
-		(float)X, (float)Y,
-		(float)Wd, (float)Ht);
+		intendedX, intendedY,
+		intendedWd, intendedHt,
+		X, Y,
+		Wd, Ht);
 
 	// Some games set invalid values for z-min and z-max so fix them to the max and min allowed and let the shaders do this work
-	D3D11_VIEWPORT vp = CD3D11_VIEWPORT((float)X, (float)Y,
-										(float)Wd, (float)Ht,
+	D3D11_VIEWPORT vp = CD3D11_VIEWPORT(X, Y,
+										Wd, Ht,
 										0.f,	// (xfregs.viewport.farZ - xfregs.viewport.zRange) / 16777216.0f;
 										1.f);   //  xfregs.viewport.farZ / 16777216.0f;
 	D3D::context->RSSetViewports(1, &vp);
diff --git a/Source/Core/VideoBackends/OGL/Src/GLUtil.h b/Source/Core/VideoBackends/OGL/Src/GLUtil.h
index 54a2ac5735..4dbbd06e05 100644
--- a/Source/Core/VideoBackends/OGL/Src/GLUtil.h
+++ b/Source/Core/VideoBackends/OGL/Src/GLUtil.h
@@ -33,6 +33,7 @@
 #define glDrawElementsBaseVertex(...)
 #define glDrawRangeElementsBaseVertex(...)
 #define glRenderbufferStorageMultisampleCoverageNV(...) 
+#define glViewportIndexedf(...)
 #endif
 #else
 #define TEX2D	GL_TEXTURE_RECTANGLE_ARB
diff --git a/Source/Core/VideoBackends/OGL/Src/Render.cpp b/Source/Core/VideoBackends/OGL/Src/Render.cpp
index 4dca112031..e507fc45cd 100644
--- a/Source/Core/VideoBackends/OGL/Src/Render.cpp
+++ b/Source/Core/VideoBackends/OGL/Src/Render.cpp
@@ -386,6 +386,7 @@ Renderer::Renderer()
 	g_ogl_config.bSupportCoverageMSAA = false; // XXX: GLES3 spec has MSAA
 	g_ogl_config.bSupportSampleShading = false; 
 	g_ogl_config.bSupportOGL31 = false; 
+	g_ogl_config.bSupportViewportFloat = false;
 	if (DriverDetails::HasBug(DriverDetails::BUG_ISTEGRA) || DriverDetails::HasBug(DriverDetails::BUG_ISPOWERVR))
 		g_ogl_config.eSupportedGLSLVersion = GLSLES2;
 	else
@@ -496,6 +497,7 @@ Renderer::Renderer()
 	g_ogl_config.bSupportCoverageMSAA = GLEW_NV_framebuffer_multisample_coverage;
 	g_ogl_config.bSupportSampleShading = GLEW_ARB_sample_shading;
 	g_ogl_config.bSupportOGL31 = GLEW_VERSION_3_1;
+	g_ogl_config.bSupportViewportFloat = GLEW_ARB_viewport_array;
 
 	if(strstr(g_ogl_config.glsl_version, "1.00") || strstr(g_ogl_config.glsl_version, "1.10") || strstr(g_ogl_config.glsl_version, "1.20"))
 	{
@@ -1105,12 +1107,12 @@ void Renderer::UpdateViewport(Matrix44& vpCorrection)
 	int scissorYOff = bpmem.scissorOffset.y * 2;
 
 	// TODO: ceil, floor or just cast to int?
-	int X = EFBToScaledX((int)ceil(xfregs.viewport.xOrig - xfregs.viewport.wd - (float)scissorXOff));
-	int Y = EFBToScaledY((int)ceil((float)EFB_HEIGHT - xfregs.viewport.yOrig + xfregs.viewport.ht + (float)scissorYOff));
-	int Width = EFBToScaledX((int)ceil(2.0f * xfregs.viewport.wd));
-	int Height = EFBToScaledY((int)ceil(-2.0f * xfregs.viewport.ht));
-	double GLNear = (xfregs.viewport.farZ - xfregs.viewport.zRange) / 16777216.0f;
-	double GLFar = xfregs.viewport.farZ / 16777216.0f;
+	float X = EFBToScaledXf(xfregs.viewport.xOrig - xfregs.viewport.wd - (float)scissorXOff);
+	float Y = EFBToScaledYf((float)EFB_HEIGHT - xfregs.viewport.yOrig + xfregs.viewport.ht + (float)scissorYOff);
+	float Width = EFBToScaledXf(2.0f * xfregs.viewport.wd);
+	float Height = EFBToScaledYf(-2.0f * xfregs.viewport.ht);
+	float GLNear = (xfregs.viewport.farZ - xfregs.viewport.zRange) / 16777216.0f;
+	float GLFar = xfregs.viewport.farZ / 16777216.0f;
 	if (Width < 0)
 	{
 		X += Width;
@@ -1126,7 +1128,14 @@ void Renderer::UpdateViewport(Matrix44& vpCorrection)
 	Matrix44::LoadIdentity(vpCorrection);
 
 	// Update the view port
-	glViewport(X, Y, Width, Height);
+	if(g_ogl_config.bSupportViewportFloat)
+	{
+		glViewportIndexedf(0, X, Y, Width, Height);
+	}
+	else
+	{
+		glViewport(round(X), round(Y), round(Width), round(Height));
+	}
 	glDepthRangef(GLNear, GLFar);
 }
 
diff --git a/Source/Core/VideoBackends/OGL/Src/Render.h b/Source/Core/VideoBackends/OGL/Src/Render.h
index 8c6a8ca8f8..efafb8708d 100644
--- a/Source/Core/VideoBackends/OGL/Src/Render.h
+++ b/Source/Core/VideoBackends/OGL/Src/Render.h
@@ -27,6 +27,7 @@ extern struct VideoConfig {
 	bool bSupportSampleShading;
 	GLSL_VERSION eSupportedGLSLVersion;
 	bool bSupportOGL31;
+	bool bSupportViewportFloat;
 	
 	const char *gl_vendor;
 	const char *gl_renderer;