diff --git a/dist/iidx/iidxio-bio2.conf b/dist/iidx/iidxio-bio2.conf
index f87e2d7..4b42af0 100644
--- a/dist/iidx/iidxio-bio2.conf
+++ b/dist/iidx/iidxio-bio2.conf
@@ -1,7 +1,7 @@
 # Autodetect BIO2 port (default: on)
 bio2.autodetect=true
 
-# BIO2 serial port
+# BIO2 serial port. Optional, if autodetect property is turned on
 bio2.port=COM4
 
 # BIO2 bus baudrate (real devices expect 115200)
diff --git a/src/main/bio2drv/config-bio2.c b/src/main/bio2drv/config-bio2.c
index 2a68cc1..492cdef 100644
--- a/src/main/bio2drv/config-bio2.c
+++ b/src/main/bio2drv/config-bio2.c
@@ -24,7 +24,7 @@ void bio2drv_config_bio2_init(struct cconfig *config)
         config,
         BIO2DRV_CONFIG_BIO2_PORT_KEY,
         BIO2DRV_CONFIG_BIO2_DEFAULT_PORT_VALUE,
-        "BIO2 serial port");
+        "BIO2 serial port. Optional, if autodetect property is turned on");
 
     cconfig_util_set_int(
         config,