diff --git a/tools/vio2sf/src/vio2sf/desmume/SPU.cpp b/tools/vio2sf/src/vio2sf/desmume/SPU.cpp
index eea2f48db..8757a3ba6 100644
--- a/tools/vio2sf/src/vio2sf/desmume/SPU.cpp
+++ b/tools/vio2sf/src/vio2sf/desmume/SPU.cpp
@@ -521,13 +521,12 @@ extern "C" void SPU_WriteLong(u32 addr, u32 val)
 }
 
 //////////////////////////////////////////////////////////////////////////////
-static FORCEINLINE s32 Interpolate(SPUInterpolationMode INTERPOLATE_MODE, s32 a, s32 b, double _ratio)
+static FORCEINLINE s32 Interpolate(SPUInterpolationMode INTERPOLATE_MODE, s32 a, s32 b, double ratio)
 {
-	float ratio = (float)_ratio;
 	if(INTERPOLATE_MODE == SPUInterpolation_Cosine)
 	{
 		//why did we change it away from the lookup table? somebody should research that
-		ratio = ratio - (int)ratio;
+		ratio = ratio - sputrunc(ratio);
 		double ratio2 = ((1.0 - cos(ratio * M_PI)) * 0.5);
 		//double ratio2 = (1.0f - cos_lut[((int)(ratio*256.0))&0xFF]) / 2.0f;
 		return (s32)(((1-ratio2)*a) + (ratio2*b));