diff --git a/libraries/AP_HAL_Empty/RCInput.h b/libraries/AP_HAL_Empty/RCInput.h
index ecde9697c7..8fd0a818c2 100644
--- a/libraries/AP_HAL_Empty/RCInput.h
+++ b/libraries/AP_HAL_Empty/RCInput.h
@@ -10,4 +10,6 @@ public:
     uint8_t num_channels() override;
     uint16_t read(uint8_t ch) override;
     uint8_t read(uint16_t* periods, uint8_t len) override;
+    virtual const char *protocol() const override { return "Empty"; }
+
 };