diff --git a/libraries/AP_DAL/AP_DAL_InertialSensor.cpp b/libraries/AP_DAL/AP_DAL_InertialSensor.cpp
index 0b1abbdbba..36d0dc205c 100644
--- a/libraries/AP_DAL/AP_DAL_InertialSensor.cpp
+++ b/libraries/AP_DAL/AP_DAL_InertialSensor.cpp
@@ -51,6 +51,10 @@ void AP_DAL_InertialSensor::start_frame()
 // update filtered gyro and accel
 void AP_DAL_InertialSensor::update_filtered(uint8_t i)
 {
-    gyro_filtered[i] = gyro_filtered[i] * alpha + (_RISI[i].delta_angle/_RISI[i].delta_angle_dt) * (1-alpha);
-    accel_filtered[i] = accel_filtered[i] * alpha + (_RISI[i].delta_velocity/_RISI[i].delta_velocity_dt) * (1-alpha);
+    if (is_positive(_RISI[i].delta_angle_dt)) {
+        gyro_filtered[i] = gyro_filtered[i] * alpha + (_RISI[i].delta_angle/_RISI[i].delta_angle_dt) * (1-alpha);
+    }
+    if (is_positive(_RISI[i].delta_velocity_dt)) {
+        accel_filtered[i] = accel_filtered[i] * alpha + (_RISI[i].delta_velocity/_RISI[i].delta_velocity_dt) * (1-alpha);
+    }
 }