diff --git a/libraries/AP_RPM/AP_RPM.h b/libraries/AP_RPM/AP_RPM.h
index bc66c7937f..82df5e21eb 100644
--- a/libraries/AP_RPM/AP_RPM.h
+++ b/libraries/AP_RPM/AP_RPM.h
@@ -116,8 +116,6 @@ private:
     AP_RPM_Backend *drivers[RPM_MAX_INSTANCES];
     uint8_t num_instances;
 
-    void detect_instance(uint8_t instance);
-
     void Log_RPM() const;
 };
 
diff --git a/libraries/AP_RPM/RPM_Backend.cpp b/libraries/AP_RPM/RPM_Backend.cpp
index a22e44102c..9c90fb56a5 100644
--- a/libraries/AP_RPM/RPM_Backend.cpp
+++ b/libraries/AP_RPM/RPM_Backend.cpp
@@ -17,8 +17,6 @@
 
 #if AP_RPM_ENABLED
 
-#include <AP_Common/AP_Common.h>
-#include <AP_HAL/AP_HAL.h>
 #include "AP_RPM.h"
 
 /*
diff --git a/libraries/AP_RPM/RPM_EFI.cpp b/libraries/AP_RPM/RPM_EFI.cpp
index bca16706fc..1cfa0ad011 100644
--- a/libraries/AP_RPM/RPM_EFI.cpp
+++ b/libraries/AP_RPM/RPM_EFI.cpp
@@ -24,7 +24,6 @@
 AP_RPM_EFI::AP_RPM_EFI(AP_RPM &_ap_rpm, uint8_t _instance, AP_RPM::RPM_State &_state) :
     AP_RPM_Backend(_ap_rpm, _instance, _state)
 {
-    instance = _instance;
 }
 
 void AP_RPM_EFI::update(void)
diff --git a/libraries/AP_RPM/RPM_EFI.h b/libraries/AP_RPM/RPM_EFI.h
index a676b1bb67..76710a3009 100644
--- a/libraries/AP_RPM/RPM_EFI.h
+++ b/libraries/AP_RPM/RPM_EFI.h
@@ -30,7 +30,6 @@ public:
     void update(void) override;
 
 private:
-    uint8_t instance;
 };
 
 #endif
diff --git a/libraries/AP_RPM/RPM_ESC_Telem.cpp b/libraries/AP_RPM/RPM_ESC_Telem.cpp
index 3c4dbd2bd3..97a12770e9 100644
--- a/libraries/AP_RPM/RPM_ESC_Telem.cpp
+++ b/libraries/AP_RPM/RPM_ESC_Telem.cpp
@@ -28,7 +28,6 @@ extern const AP_HAL::HAL& hal;
 AP_RPM_ESC_Telem::AP_RPM_ESC_Telem(AP_RPM &_ap_rpm, uint8_t _instance, AP_RPM::RPM_State &_state) :
     AP_RPM_Backend(_ap_rpm, _instance, _state)
 {
-    instance = _instance;
 }
 
 
diff --git a/libraries/AP_RPM/RPM_ESC_Telem.h b/libraries/AP_RPM/RPM_ESC_Telem.h
index df127fb600..e8ef243871 100644
--- a/libraries/AP_RPM/RPM_ESC_Telem.h
+++ b/libraries/AP_RPM/RPM_ESC_Telem.h
@@ -28,7 +28,6 @@ public:
     // update state
     void update(void) override;
 private:
-    uint8_t instance;
 };
 
 #endif  // AP_RPM_ESC_TELEM_ENABLED
diff --git a/libraries/AP_RPM/RPM_HarmonicNotch.cpp b/libraries/AP_RPM/RPM_HarmonicNotch.cpp
index 144a30bcb6..e5dbbe766c 100644
--- a/libraries/AP_RPM/RPM_HarmonicNotch.cpp
+++ b/libraries/AP_RPM/RPM_HarmonicNotch.cpp
@@ -23,7 +23,6 @@
 AP_RPM_HarmonicNotch::AP_RPM_HarmonicNotch(AP_RPM &_ap_rpm, uint8_t _instance, AP_RPM::RPM_State &_state) :
     AP_RPM_Backend(_ap_rpm, _instance, _state)
 {
-    instance = _instance;
 }
 
 void AP_RPM_HarmonicNotch::update(void)
diff --git a/libraries/AP_RPM/RPM_HarmonicNotch.h b/libraries/AP_RPM/RPM_HarmonicNotch.h
index 78d9a3081f..81d13a4cfa 100644
--- a/libraries/AP_RPM/RPM_HarmonicNotch.h
+++ b/libraries/AP_RPM/RPM_HarmonicNotch.h
@@ -29,7 +29,7 @@ public:
     void update(void) override;
 
 private:
-    uint8_t instance;
+
 };
 
 #endif  // AP_RPM_HARMONICNOTCH_ENABLED