diff --git a/libraries/AP_Relay/AP_Relay.cpp b/libraries/AP_Relay/AP_Relay.cpp
index d83dd6121f..fb0a1db612 100644
--- a/libraries/AP_Relay/AP_Relay.cpp
+++ b/libraries/AP_Relay/AP_Relay.cpp
@@ -152,6 +152,18 @@ void AP_Relay::toggle(uint8_t instance)
     }
 }
 
+// check settings are valid
+bool AP_Relay::arming_checks(size_t buflen, char *buffer) const
+{
+    for (uint8_t i=0; i<AP_RELAY_NUM_RELAYS; i++) {
+        if (_pin[i] != -1 && !hal.gpio->valid_pin(_pin[i])) {
+            hal.util->snprintf(buffer, buflen, "Relay[%u] pin %d invalid", i + 1, _pin[i]);
+            return false;
+        }
+    }
+    return true;
+}
+
 namespace AP {
 
 AP_Relay *relay()
diff --git a/libraries/AP_Relay/AP_Relay.h b/libraries/AP_Relay/AP_Relay.h
index c8c5295ef7..a13748d9d5 100644
--- a/libraries/AP_Relay/AP_Relay.h
+++ b/libraries/AP_Relay/AP_Relay.h
@@ -38,6 +38,9 @@ public:
     // toggle the relay status
     void        toggle(uint8_t instance);
 
+    // check settings are valid
+    bool arming_checks(size_t buflen, char *buffer) const;
+    
     static AP_Relay *get_singleton(void) {return singleton; }
 
     static const struct AP_Param::GroupInfo        var_info[];