diff --git a/libraries/AP_Motors/AP_MotorsHeli.cpp b/libraries/AP_Motors/AP_MotorsHeli.cpp
index b5c17b849d..2c357c31c2 100644
--- a/libraries/AP_Motors/AP_MotorsHeli.cpp
+++ b/libraries/AP_Motors/AP_MotorsHeli.cpp
@@ -356,6 +356,14 @@ void AP_MotorsHeli::reset_swash_servo(RC_Channel& servo)
 void AP_MotorsHeli::update_throttle_filter()
 {
     _throttle_filter.apply(_throttle_in, 1.0f/_loop_rate);
+
+    // constrain filtered throttle
+    if (_throttle_filter.get() < 0.0f) {
+        _throttle_filter.reset(0.0f);
+    }
+    if (_throttle_filter.get() > 1.0f) {
+        _throttle_filter.reset(1.0f);
+    }
 }
 
 // reset_flight_controls - resets all controls and scalars to flight status