diff --git a/libraries/AP_RPM/AP_RPM.cpp b/libraries/AP_RPM/AP_RPM.cpp
index 5d229b759f..630c9f5aee 100644
--- a/libraries/AP_RPM/AP_RPM.cpp
+++ b/libraries/AP_RPM/AP_RPM.cpp
@@ -105,12 +105,17 @@ void AP_RPM::init(void)
         return;
     }
     for (uint8_t i=0; i<RPM_MAX_INSTANCES; i++) {
-        const uint8_t type = _type[i];
+        uint8_t type = _type[i];
 
 #if (CONFIG_HAL_BOARD == HAL_BOARD_PX4) || ((CONFIG_HAL_BOARD == HAL_BOARD_VRBRAIN) && (!defined(CONFIG_ARCH_BOARD_VRBRAIN_V51) && !defined(CONFIG_ARCH_BOARD_VRUBRAIN_V52)))
         if (type == RPM_TYPE_PX4_PWM) {
             drivers[i] = new AP_RPM_PX4_PWM(*this, i, state[i]);
         }
+#else
+        if (type == RPM_TYPE_PX4_PWM) {
+            // on non-PX4 treat PX4-pin as AUXPIN option, for upgrade
+            type = RPM_TYPE_PIN;
+        }
 #endif
         if (type == RPM_TYPE_PIN) {
             drivers[i] = new AP_RPM_Pin(*this, i, state[i]);