diff --git a/APMrover2/Parameters.cpp b/APMrover2/Parameters.cpp
index d62133cce6..c28d0faa1b 100644
--- a/APMrover2/Parameters.cpp
+++ b/APMrover2/Parameters.cpp
@@ -332,13 +332,17 @@ const AP_Param::Info Rover::var_info[] = {
     GOBJECT(gps, "GPS_", AP_GPS),
 
 #if AP_AHRS_NAVEKF_AVAILABLE
+#if HAL_NAVEKF2_AVAILABLE
     // @Group: EK2_
     // @Path: ../libraries/AP_NavEKF2/AP_NavEKF2.cpp
     GOBJECTN(ahrs.EKF2, NavEKF2, "EK2_", NavEKF2),
+#endif
 
+#if HAL_NAVEKF3_AVAILABLE
     // @Group: EK3_
     // @Path: ../libraries/AP_NavEKF3/AP_NavEKF3.cpp
     GOBJECTN(ahrs.EKF3, NavEKF3, "EK3_", NavEKF3),
+#endif
 #endif
 
     // @Group: RPM
diff --git a/APMrover2/sensors.cpp b/APMrover2/sensors.cpp
index 37fc5e1d1e..f62c3c3b04 100644
--- a/APMrover2/sensors.cpp
+++ b/APMrover2/sensors.cpp
@@ -60,7 +60,9 @@ void Rover::update_wheel_encoder()
     const uint32_t now_ms = AP_HAL::millis();
 
     // calculate angular change (in radians)
+#if HAL_NAVEKF3_AVAILABLE
     const float delta_angle = curr_angle_rad - wheel_encoder_last_angle_rad[wheel_encoder_last_index_sent];
+#endif
     wheel_encoder_last_angle_rad[wheel_encoder_last_index_sent] = curr_angle_rad;
 
     // calculate delta time using time between sensor readings or time since last send to ekf (whichever is shorter)
@@ -72,6 +74,7 @@ void Rover::update_wheel_encoder()
     } else {
         wheel_encoder_last_reading_ms[wheel_encoder_last_index_sent] = sensor_reading_ms;
     }
+#if HAL_NAVEKF3_AVAILABLE
     const float delta_time = sensor_diff_ms * 0.001f;
 
     /* delAng is the measured change in angular position from the previous measurement where a positive rotation is produced by forward motion of the vehicle (rad)
@@ -84,6 +87,7 @@ void Rover::update_wheel_encoder()
                         wheel_encoder_last_reading_ms[wheel_encoder_last_index_sent],
                         g2.wheel_encoder.get_pos_offset(wheel_encoder_last_index_sent),
                         g2.wheel_encoder.get_wheel_radius(wheel_encoder_last_index_sent));
+#endif
 }
 
 // Accel calibration