diff --git a/Source/Core/VideoBackends/Software/Rasterizer.cpp b/Source/Core/VideoBackends/Software/Rasterizer.cpp
index e4ebdd1234..9db10f8ae0 100644
--- a/Source/Core/VideoBackends/Software/Rasterizer.cpp
+++ b/Source/Core/VideoBackends/Software/Rasterizer.cpp
@@ -264,7 +264,8 @@ static void BuildBlock(s32 blockX, s32 blockY)
   }
 }
 
-void DrawTriangleFrontFace(OutputVertexData* v0, OutputVertexData* v1, OutputVertexData* v2)
+void DrawTriangleFrontFace(const OutputVertexData* v0, const OutputVertexData* v1,
+                           const OutputVertexData* v2)
 {
   INCSTAT(stats.thisFrame.numTrianglesDrawn);
 
diff --git a/Source/Core/VideoBackends/Software/Rasterizer.h b/Source/Core/VideoBackends/Software/Rasterizer.h
index 50308b7449..29fa6d6dee 100644
--- a/Source/Core/VideoBackends/Software/Rasterizer.h
+++ b/Source/Core/VideoBackends/Software/Rasterizer.h
@@ -12,7 +12,8 @@ namespace Rasterizer
 {
 void Init();
 
-void DrawTriangleFrontFace(OutputVertexData* v0, OutputVertexData* v1, OutputVertexData* v2);
+void DrawTriangleFrontFace(const OutputVertexData* v0, const OutputVertexData* v1,
+                           const OutputVertexData* v2);
 
 void SetTevReg(int reg, int comp, s16 color);
 
@@ -22,7 +23,7 @@ struct Slope
   float dfdy;
   float f0;
 
-  float GetValue(float dx, float dy) { return f0 + (dfdx * dx) + (dfdy * dy); }
+  float GetValue(float dx, float dy) const { return f0 + (dfdx * dx) + (dfdy * dy); }
 };
 
 struct RasterBlockPixel