diff --git a/libraries/AC_AttitudeControl/AC_AttitudeControl_Heli.cpp b/libraries/AC_AttitudeControl/AC_AttitudeControl_Heli.cpp
index f865266a0bbb6..39c9ad277e982 100644
--- a/libraries/AC_AttitudeControl/AC_AttitudeControl_Heli.cpp
+++ b/libraries/AC_AttitudeControl/AC_AttitudeControl_Heli.cpp
@@ -569,7 +569,8 @@ float AC_AttitudeControl_Heli::get_throttle_boosted(float throttle_in)
     float boost_factor = 1.0f / constrain_float(cos_tilt_target, 0.1f, 1.0f);
 
     // angle boost and inverted factor applied about the zero thrust collective
-    float throttle_out = (throttle_in - ((AP_MotorsHeli&)_motors).get_coll_mid()) * inverted_factor * boost_factor + ((AP_MotorsHeli&)_motors).get_coll_mid();
+    const float coll_mid = ((AP_MotorsHeli&)_motors).get_coll_mid();
+    float throttle_out = ((throttle_in - coll_mid)  * inverted_factor * boost_factor) + coll_mid;
     _angle_boost = constrain_float(throttle_out - throttle_in, -1.0f, 1.0f);
     return throttle_out;
 }
diff --git a/libraries/AC_AttitudeControl/AC_AttitudeControl_Heli.h b/libraries/AC_AttitudeControl/AC_AttitudeControl_Heli.h
index 996439f631f91..b2695b59cfa03 100644
--- a/libraries/AC_AttitudeControl/AC_AttitudeControl_Heli.h
+++ b/libraries/AC_AttitudeControl/AC_AttitudeControl_Heli.h
@@ -90,10 +90,10 @@ class AC_AttitudeControl_Heli : public AC_AttitudeControl {
     void input_thrust_vector_heading(const Vector3f& thrust_vector, float heading_angle_cd, float heading_rate_cds) override;
 
     // enable/disable inverted flight
-    void set_inverted_flight(bool inverted) override { _inverted_flight = inverted;}
+    void set_inverted_flight(bool inverted) override { _inverted_flight = inverted; }
 
     // accessor for inverted flight flag
-    bool get_inverted_flight() override { return _inverted_flight;}
+    bool get_inverted_flight() override { return _inverted_flight; }
 
     // set the PID notch sample rates
     void set_notch_sample_rate(float sample_rate) override;
@@ -136,7 +136,7 @@ class AC_AttitudeControl_Heli : public AC_AttitudeControl {
     float _passthrough_yaw;
 
     // get_roll_trim - angle in centi-degrees to be added to roll angle. Used by helicopter to counter tail rotor thrust in hover
-    float get_roll_trim_rad() override { return constrain_float(radians(get_roll_trim_cd() * 0.01f), -radians(10.0f),radians(10.0f));}
+    float get_roll_trim_rad() override { return radians(get_roll_trim_cd() * 0.01); }
 
     // internal variables
     float _hover_roll_trim_scalar = 0;              // scalar used to suppress Hover Roll Trim