diff --git a/src/engine/engine_util_spatial.h b/src/engine/engine_util_spatial.h
index e704facb..6a53ddfd 100644
--- a/src/engine/engine_util_spatial.h
+++ b/src/engine/engine_util_spatial.h
@@ -95,11 +95,11 @@ void mju_crossMotion(mjtNum res[6], const mjtNum vel[6], const mjtNum v[6]);
 void mju_crossForce(mjtNum res[6], const mjtNum vel[6], const mjtNum f[6]);
 
 // express inertia in com-based frame
-void mju_inertCom(mjtNum res[10], const mjtNum inert[3], const mjtNum mat[9],
+void mju_inertCom(mjtNum* res, const mjtNum inert[3], const mjtNum mat[9],
                   const mjtNum dif[3], mjtNum mass);
 
 // express motion axis in com-based frame
-void mju_dofCom(mjtNum res[6], const mjtNum axis[3], const mjtNum offset[3]);
+void mju_dofCom(mjtNum* res, const mjtNum axis[3], const mjtNum offset[3]);
 
 // multiply 6D vector (rotation, translation) by 6D inertia matrix
 MJAPI void mju_mulInertVec(mjtNum* res, const mjtNum inert[10], const mjtNum vec[6]);