diff --git a/stepmania/src/Model.cpp b/stepmania/src/Model.cpp
index 903e3d3616..219e4e43aa 100644
--- a/stepmania/src/Model.cpp
+++ b/stepmania/src/Model.cpp
@@ -676,22 +676,18 @@ void Model::SetBones( const msAnimation* pAnimation, float fFrame, vector<myBone
 			{
 				const float s = SCALE( fFrame, pLastRotationKey->fTime, pThisRotationKey->fTime, 0, 1 );
 
-				RageVector4 q1, q2, q;
-				RageQuatFromHPR( &q1, pLastRotationKey->Rotation );
-				RageQuatFromHPR( &q2, pThisRotationKey->Rotation );
-				RageQuatSlerp( &q, q1, q2, s );
+				RageVector4 q;
+				RageQuatSlerp( &q, pLastRotationKey->Rotation, pThisRotationKey->Rotation, s );
 
 				RageMatrixFromQuat( &m, q );
 			}
 			else if( pLastRotationKey == 0 )
 			{
-				vRot = pThisRotationKey->Rotation;
-				RageMatrixAngles( &m, vRot );
+				RageMatrixFromQuat( &m, pThisRotationKey->Rotation );
 			}
 			else if( pThisRotationKey == 0 )
 			{
-				vRot = pLastRotationKey->Rotation;
-				RageMatrixAngles( &m, vRot );
+				RageMatrixFromQuat( &m, pLastRotationKey->Rotation );
 			}
 			m.m[3][0] = vPos[0];
 			m.m[3][1] = vPos[1];
diff --git a/stepmania/src/ModelTypes.cpp b/stepmania/src/ModelTypes.cpp
index 1710527323..f9e5630b74 100644
--- a/stepmania/src/ModelTypes.cpp
+++ b/stepmania/src/ModelTypes.cpp
@@ -340,7 +340,8 @@ bool msAnimation::LoadMilkshapeAsciiBones( RString sAniName, RString sPath )
 
 				msRotationKey key;
 				key.fTime = fTime;
-				key.Rotation = RageVector3( Rotation[0], Rotation[1], Rotation[2] );
+				RageVector3 Rotation = RageVector3( Rotation[0], Rotation[1], Rotation[2] );
+				RageQuatFromHPR( &key.Rotation, Rotation );
 				Bone.RotationKeys[j] = key;
 			}
 		}
diff --git a/stepmania/src/ModelTypes.h b/stepmania/src/ModelTypes.h
index fb87ec263b..bc0ba114da 100644
--- a/stepmania/src/ModelTypes.h
+++ b/stepmania/src/ModelTypes.h
@@ -110,7 +110,7 @@ struct msPositionKey
 struct msRotationKey
 {
 	float fTime;
-	RageVector3 Rotation;
+	RageVector4 Rotation;
 };
 
 struct msBone