diff --git a/libraries/AP_RPM/AP_RPM.h b/libraries/AP_RPM/AP_RPM.h
index 87e6693f9d..1c782cde97 100644
--- a/libraries/AP_RPM/AP_RPM.h
+++ b/libraries/AP_RPM/AP_RPM.h
@@ -102,7 +102,6 @@ private:
     uint8_t num_instances:2;
 
     void detect_instance(uint8_t instance);
-    void update_instance(uint8_t instance);
 };
 
 namespace AP {