diff --git a/src/modules/mavlink/streams/RAW_RPM.hpp b/src/modules/mavlink/streams/RAW_RPM.hpp
index d0a09c9495..ffa4001cb0 100644
--- a/src/modules/mavlink/streams/RAW_RPM.hpp
+++ b/src/modules/mavlink/streams/RAW_RPM.hpp
@@ -49,7 +49,7 @@ public:
 
 	unsigned get_size() override
 	{
-		return _rpm_sub.advertised() ? MAVLINK_MSG_ID_RAW_RPM + MAVLINK_NUM_NON_PAYLOAD_BYTES : 0;
+		return _rpm_sub.advertised() ? (MAVLINK_MSG_ID_RAW_RPM_LEN + MAVLINK_NUM_NON_PAYLOAD_BYTES) : 0;
 	}
 
 private: