diff --git a/desmume/src/gfx3d.cpp b/desmume/src/gfx3d.cpp
index 8504a2e60..80d52d732 100644
--- a/desmume/src/gfx3d.cpp
+++ b/desmume/src/gfx3d.cpp
@@ -1749,10 +1749,21 @@ static void gfx3d_glVecTest(u32 v)
 
 void VIEWPORT::decode(const u32 v)
 {
-	this->x = (v & 0xFF);
-	this->y = std::min<u8>(191, (v >> 8) & 0xFF);
-	this->width = ((v >> 16) & 0xFF) + 1 - this->x;
-	this->height = std::min<u8>(191, (v >> 24) & 0xFF) + 1 - this->y;
+	//test: homie rollerz character select chooses nonsense for Y. they did the math backwards. their goal was a fullscreen viewport, they just messed up.
+	//they also messed up the width...
+
+	u8 x1 = (v>> 0)&0xFF;
+	u8 y1 = (v>> 8)&0xFF;
+	u8 x2 = (v>>16)&0xFF;
+	u8 y2 = (v>>24)&0xFF;
+
+	//I'm 100% sure this is basically 99% correct
+	//the modular math is right. the details of how the +1 is handled may be wrong (this might should be dealt with in the viewport transformation instead)
+	//Its an off by one error in any event so we may never know
+	width = (u8)(x2-x1)+1;
+	height = (u8)(y2-y1)+1;
+	x = x1;
+	y = y1;
 }
 
 void gfx3d_glFogColor(u32 v)
diff --git a/desmume/src/rasterize.cpp b/desmume/src/rasterize.cpp
index 14a460b63..787a6363a 100644
--- a/desmume/src/rasterize.cpp
+++ b/desmume/src/rasterize.cpp
@@ -1519,11 +1519,22 @@ template<bool CUSTOM> void SoftRasterizerRenderer::performViewportTransforms()
 			vert.coord[1] *= viewport.height * yfactor;
 			vert.coord[1] += viewport.y * yfactor;
 			vert.coord[1] = ymax - vert.coord[1];
+
+			//this is required to fix Homie Rollerz character select.
+			//this was also a better fix for Princess Debut's giant out of range polys.
+			//Basically, invalid viewports are blithely used here, and the math overflows and wraps around
+			//NOTE: this is a crude approximation of the correct fixed point modular arithmetic
+			if(vert.coord[0] >= 256) vert.coord[0] -= 256;
+			if(vert.coord[1] >= 256) vert.coord[1] -= 256;
+			if(vert.coord[0] < 0) vert.coord[0] += 256;
+			if(vert.coord[1] < 0) vert.coord[1] += 256;
 			
-			//well, i guess we need to do this to keep Princess Debut from rendering huge polys.
-			//there must be something strange going on
-			vert.coord[0] = max(0.0f,min(xmax,vert.coord[0]));
-			vert.coord[1] = max(0.0f,min(ymax,vert.coord[1]));
+			//now, this is really lame. probably the rasterizer should be dealing with this, but 
+			//1. its easier here
+			//2. its more likely reusable in opengl this way (well, this is a bunch more calculations that should be earlier in the pipeline and obligatorily shared)
+			//I do have some evidence that this wrecks the hardware extremely, but nothing's likely to use that effect.
+			//This is a sanity check only.
+			if(vert.coord[1] >= 192) vert.coord[1] = 192;
 		}
 	}
 }