diff --git a/src/modules/mavlink/mavlink_receiver.cpp b/src/modules/mavlink/mavlink_receiver.cpp
index 0c2180a4d8..d139ac99dd 100644
--- a/src/modules/mavlink/mavlink_receiver.cpp
+++ b/src/modules/mavlink/mavlink_receiver.cpp
@@ -1837,8 +1837,10 @@ MavlinkReceiver::receive_thread(void *arg)
 				}
 			}
 
-			/* count received bytes */
-			_mavlink->count_rxbytes(nread);
+			/* count received bytes (nread will be -1 on read error) */
+			if (nread > 0) {
+				_mavlink->count_rxbytes(nread);
+			}
 		}
 	}