diff --git a/gear_sonic_deploy/src/g1/g1_deploy_onnx_ref/src/g1_deploy_onnx_ref.cpp b/gear_sonic_deploy/src/g1/g1_deploy_onnx_ref/src/g1_deploy_onnx_ref.cpp
index 6659ac4..3b6430f 100644
--- a/gear_sonic_deploy/src/g1/g1_deploy_onnx_ref/src/g1_deploy_onnx_ref.cpp
+++ b/gear_sonic_deploy/src/g1/g1_deploy_onnx_ref/src/g1_deploy_onnx_ref.cpp
@@ -2840,6 +2840,10 @@ class G1Deploy {
       // MuJoCo index 14 = waist_pitch_joint. Positive = forward lean.
       double waist_offset_rad = g_waist_pitch_offset_deg.load() * M_PI / 180.0;
       motor_command_tmp.q_target.at(14) += static_cast<float>(waist_offset_rad);
+      // Stiffen waist pitch to actually track the offset (default Kp=28.5 too
+      // weak to overcome gravity on upper body). Match hip-level stiffness.
+      motor_command_tmp.kp.at(14) = 100.0f;
+      motor_command_tmp.kd.at(14) = 5.0f;
 
       motor_command_buffer_.SetData(motor_command_tmp);
       return true;