diff --git a/libraries/AP_RobotisServo/AP_RobotisServo.cpp b/libraries/AP_RobotisServo/AP_RobotisServo.cpp
index 3e90b54917..e4dc7eddff 100644
--- a/libraries/AP_RobotisServo/AP_RobotisServo.cpp
+++ b/libraries/AP_RobotisServo/AP_RobotisServo.cpp
@@ -340,7 +340,7 @@ void AP_RobotisServo::process_packet(const uint8_t *pkt, uint8_t length)
         // easier
         return;
     }
-    uint16_t id_mask = (1U<<(id-1));
+    uint32_t id_mask = (1U<<(id-1));
     if (!(id_mask & servo_mask)) {
         // mark the servo as present
         servo_mask |= id_mask;
diff --git a/libraries/AP_RobotisServo/AP_RobotisServo.h b/libraries/AP_RobotisServo/AP_RobotisServo.h
index b850f51b64..d5522895a1 100644
--- a/libraries/AP_RobotisServo/AP_RobotisServo.h
+++ b/libraries/AP_RobotisServo/AP_RobotisServo.h
@@ -58,7 +58,7 @@ private:
     void configure_servos(void);
 
     // auto-detected mask of available servos, from a broadcast ping
-    uint16_t servo_mask;
+    uint32_t servo_mask;
     uint8_t detection_count;
     uint8_t configured_servos;
     bool initialised;