diff --git a/src/xrt/auxiliary/math/m_api.h b/src/xrt/auxiliary/math/m_api.h
index b6379b237..5416cf004 100644
--- a/src/xrt/auxiliary/math/m_api.h
+++ b/src/xrt/auxiliary/math/m_api.h
@@ -477,6 +477,17 @@ math_matrix_3x3_transform_vec3(const struct xrt_matrix_3x3 *left,
                                const struct xrt_vec3 *right,
                                struct xrt_vec3 *result_out);
 
+/*!
+ * Transform a vec3 by a 4x4 matrix, extending the vector with w = 1.0
+ *
+ * @see xrt_matrix_4x4
+ * @ingroup aux_math
+ */
+void
+math_matrix_4x4_transform_vec3(const struct xrt_matrix_4x4 *left,
+                               const struct xrt_vec3 *right,
+                               struct xrt_vec3 *result_out);
+
 /*!
  * Transform a double vec3 by a 3x3 double matrix
  *
diff --git a/src/xrt/auxiliary/math/m_base.cpp b/src/xrt/auxiliary/math/m_base.cpp
index 6a315b0fd..00183ef7a 100644
--- a/src/xrt/auxiliary/math/m_base.cpp
+++ b/src/xrt/auxiliary/math/m_base.cpp
@@ -551,6 +551,24 @@ math_matrix_3x3_transform_vec3(const struct xrt_matrix_3x3 *left,
 	map_vec3(*result_out) = m * copy(right);
 }
 
+extern "C" void
+math_matrix_4x4_transform_vec3(const struct xrt_matrix_4x4 *left,
+                               const struct xrt_vec3 *right,
+                               struct xrt_vec3 *result_out)
+{
+	Eigen::Matrix4f m = copy(left);
+
+	Eigen::Vector4f v;
+	v << right->x, right->y, right->z, 1.0;
+
+	Eigen::Vector4f res;
+	res = m * v;
+
+	result_out->x = res.x();
+	result_out->y = res.y();
+	result_out->z = res.z();
+}
+
 extern "C" void
 math_matrix_3x3_multiply(const struct xrt_matrix_3x3 *left,
                          const struct xrt_matrix_3x3 *right,