diff --git a/conf.c b/conf.c
index 86566db..d342c8a 100644
--- a/conf.c
+++ b/conf.c
@@ -788,7 +788,7 @@ static void usage(const char *name, FILE *f, int status)
 		"  -n, --netmask MASK	Assign IPv4 MASK, dot-decimal or bits\n"
 		"    default: netmask from matching address on the host\n"
 		"  -M, --mac-addr ADDR	Use source MAC address ADDR\n"
-		"    default: MAC address from interface with default route\n"
+		"    default: 9a:55:9a:55:9a:55 (locally administered)\n"
 		"  -g, --gateway ADDR	Pass IPv4 or IPv6 address as gateway\n"
 		"    default: gateway from interface with default route\n"
 		"  -i, --interface NAME	Interface for addresses and routes\n"
diff --git a/passt.1 b/passt.1
index 02a9bcc..059abd3 100644
--- a/passt.1
+++ b/passt.1
@@ -174,8 +174,7 @@ according to the CIDR block of the assigned address (RFC 4632).
 .BR \-M ", " \-\-mac-addr " " \fIaddr
 Use source MAC address \fIaddr\fR when communicating to the guest or to the
 target namespace.
-Default is to use the MAC address of the interface with the first IPv4 default
-route on the host.
+Default is the locally administered MAC addresses 9a:55:9a:55:9a:55.
 
 .TP
 .BR \-g ", " \-\-gateway " " \fIaddr