diff --git a/src/modules/mavlink/mavlink_main.cpp b/src/modules/mavlink/mavlink_main.cpp
index fbe09564bc..861c91d471 100644
--- a/src/modules/mavlink/mavlink_main.cpp
+++ b/src/modules/mavlink/mavlink_main.cpp
@@ -483,7 +483,12 @@ Mavlink::forward_message(const mavlink_message_t *msg, Mavlink *self)
 	Mavlink *inst;
 	LL_FOREACH(_mavlink_instances, inst) {
 		if (inst != self) {
-			inst->pass_message(msg);
+
+			/* if not in normal mode, we are an onboard link
+			 * onboard links should only pass on messages from the same system ID */
+			if(!(self->_mode != MAVLINK_MODE_NORMAL && msg->sysid != mavlink_system.sysid)) {
+				inst->pass_message(msg);
+			}
 		}
 	}
 }
diff --git a/src/modules/mavlink/mavlink_receiver.cpp b/src/modules/mavlink/mavlink_receiver.cpp
index 54c412ce7c..69e3ef31d7 100644
--- a/src/modules/mavlink/mavlink_receiver.cpp
+++ b/src/modules/mavlink/mavlink_receiver.cpp
@@ -241,7 +241,8 @@ MavlinkReceiver::handle_message_command_long(mavlink_message_t *msg)
 		} else {
 
 			if (msg->sysid == mavlink_system.sysid && msg->compid == mavlink_system.compid) {
-				warnx("ignoring CMD spoofed with same SYS/COMP ID");
+				warnx("ignoring CMD spoofed with same SYS/COMP (%d/%d) ID",
+				      mavlink_system.sysid, mavlink_system.compid);
 				return;
 			}