diff --git a/LEGO1/lego/legoomni/include/legoutils.h b/LEGO1/lego/legoomni/include/legoutils.h
index ceb64416..3eece302 100644
--- a/LEGO1/lego/legoomni/include/legoutils.h
+++ b/LEGO1/lego/legoomni/include/legoutils.h
@@ -43,7 +43,7 @@ extern MxAtomId* g_isleScript;
 LegoEntity* PickEntity(MxLong, MxLong);
 LegoROI* PickROI(MxLong, MxLong);
 LegoROI* PickParentROI(MxLong p_a, MxLong p_b);
-void FUN_1003dde0(LegoROI* p_param1, MxFloat p_param2);
+void RotateY(LegoROI* p_roi, MxFloat p_angle);
 MxBool SpheresIntersect(const BoundingSphere& p_sphere1, const BoundingSphere& p_sphere2);
 MxBool FUN_1003ded0(MxFloat p_param1[2], MxFloat p_param2[3], MxFloat p_param3[3]);
 MxBool TransformWorldToScreen(const MxFloat p_world[3], MxFloat p_screen[4]);
diff --git a/LEGO1/lego/legoomni/src/build/legocarbuild.cpp b/LEGO1/lego/legoomni/src/build/legocarbuild.cpp
index 0f6306fb..d981be73 100644
--- a/LEGO1/lego/legoomni/src/build/legocarbuild.cpp
+++ b/LEGO1/lego/legoomni/src/build/legocarbuild.cpp
@@ -553,7 +553,7 @@ MxResult LegoCarBuild::Tickle()
 	}
 
 	if (m_unk0x100 == 5 && m_unk0x110) {
-		FUN_1003dde0(m_unk0x110, g_unk0x100d65a4);
+		RotateY(m_unk0x110, g_unk0x100d65a4);
 	}
 
 	if (m_unk0x10a) {
diff --git a/LEGO1/lego/legoomni/src/common/legoutils.cpp b/LEGO1/lego/legoomni/src/common/legoutils.cpp
index c5e658a6..0fcece8a 100644
--- a/LEGO1/lego/legoomni/src/common/legoutils.cpp
+++ b/LEGO1/lego/legoomni/src/common/legoutils.cpp
@@ -65,11 +65,23 @@ LegoEntity* PickEntity(MxLong, MxLong)
 	return NULL;
 }
 
-// STUB: LEGO1 0x1003dde0
-// STUB: BETA10 0x100d358e
-void FUN_1003dde0(LegoROI* p_param1, MxFloat p_param2)
+// FUNCTION: LEGO1 0x1003dde0
+// FUNCTION: BETA10 0x100d358e
+void RotateY(LegoROI* p_roi, MxFloat p_angle)
 {
-	// TODO
+	MxMatrix mat;
+	const Matrix4& local2world = p_roi->GetLocal2World();
+	mat = local2world;
+
+	float fsin = sin(p_angle);
+	float fcos = cos(p_angle);
+
+	for (MxS32 i = 0; i < 3; i++) {
+		mat[i][0] = (local2world[i][0] * fcos) + (local2world[i][2] * fsin);
+		mat[i][2] = (local2world[i][2] * fcos) - (local2world[i][0] * fsin);
+	}
+
+	p_roi->WrappedSetLocalTransform(mat);
 }
 
 // FUNCTION: LEGO1 0x1003de80