diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_HC_SR04.h b/libraries/AP_RangeFinder/AP_RangeFinder_HC_SR04.h
index bb2dd7ce68..3d80f43d24 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_HC_SR04.h
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_HC_SR04.h
@@ -33,7 +33,6 @@ private:
     uint32_t last_distance_cm;     // last distance reported (used to prevent glitches in measurement)
     uint8_t glitch_count;           // glitch counter
 
-    int8_t last_warn_echo_pin;
     AP_HAL::PWMSource pwm_source;
 
     uint32_t last_ping_ms;
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_PWM.h b/libraries/AP_RangeFinder/AP_RangeFinder_PWM.h
index 0af20c3453..e6dfd04653 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_PWM.h
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_PWM.h
@@ -44,8 +44,6 @@ protected:
 
 private:
 
-    int8_t last_warn_pin; // last pin used for reading pwm (used to recognise change in pin assignment)
-
     bool check_pin();
     void check_stop_pin();
     bool check_pins();