diff --git a/libraries/AP_HAL_SITL/SITL_State.cpp b/libraries/AP_HAL_SITL/SITL_State.cpp
index 87f1c97167..ca46800a92 100644
--- a/libraries/AP_HAL_SITL/SITL_State.cpp
+++ b/libraries/AP_HAL_SITL/SITL_State.cpp
@@ -749,10 +749,9 @@ void SITL_State::_simulator_servos(struct sitl_input &input)
     /* this maps the registers used for PWM outputs. The RC
      * driver updates these whenever it wants the channel output
      * to change */
-    uint8_t i;
 
     if (last_update_usec == 0 || !output_ready) {
-        for (i=0; i<SITL_NUM_CHANNELS; i++) {
+        for (uint8_t i=0; i<SITL_NUM_CHANNELS; i++) {
             pwm_output[i] = 1000;
         }
         if (_vehicle == ArduPlane) {
@@ -807,7 +806,7 @@ void SITL_State::_simulator_servos(struct sitl_input &input)
     input.wind.turbulence = _sitl?_sitl->wind_turbulance:0;
     input.wind.dir_z = wind_dir_z;
 
-    for (i=0; i<SITL_NUM_CHANNELS; i++) {
+    for (uint8_t i=0; i<SITL_NUM_CHANNELS; i++) {
         if (pwm_output[i] == 0xFFFF) {
             input.servos[i] = 0;
         } else {
@@ -834,7 +833,7 @@ void SITL_State::_simulator_servos(struct sitl_input &input)
         // do a little quadplane dance
         float hover_throttle = 0.0f;
         uint8_t running_motors = 0;
-        for (i=0; i < sitl_model->get_num_motors() - 1; i++) {
+        for (uint8_t i=0; i < sitl_model->get_num_motors() - 1; i++) {
             float motor_throttle = constrain_float((input.servos[sitl_model->get_motors_offset() + i] - 1000) / 1000.0f, 0.0f, 1.0f);
             // update motor_on flag
             if (!is_zero(motor_throttle)) {
@@ -857,7 +856,7 @@ void SITL_State::_simulator_servos(struct sitl_input &input)
     } else {
         // run checks on each motor
         uint8_t running_motors = 0;
-        for (i=0; i < sitl_model->get_num_motors(); i++) {
+        for (uint8_t i=0; i < sitl_model->get_num_motors(); i++) {
             float motor_throttle = constrain_float((input.servos[i] - 1000) / 1000.0f, 0.0f, 1.0f);
             // update motor_on flag
             if (!is_zero(motor_throttle)) {
@@ -880,7 +879,7 @@ void SITL_State::_simulator_servos(struct sitl_input &input)
         if (_sitl->state.battery_voltage <= 0) {
             if (_vehicle == ArduSub) {
                 voltage = _sitl->batt_voltage;
-                for (i = 0; i < 6; i++) {
+                for (uint8_t i=0; i<6; i++) {
                     float pwm = input.servos[i];
                     //printf("i: %d, pwm: %.2f\n", i, pwm);
                     float fraction = fabsf((pwm - 1500) / 500.0f);