diff --git a/run/serial.sh b/run/serial.sh
index 3f5d0e8..8c7030d 100644
--- a/run/serial.sh
+++ b/run/serial.sh
@@ -30,7 +30,7 @@ HOST_ARGS=()
 HOST_ARGS+=("-cpu=${CPU_CORES}")
 HOST_ARGS+=("-cpu_arch=${HOST_CPU}")
 
-[ -n "$HOST_MAC" ] && HOST_ARGS+=("-mac=${HOST_MAC}")
+[ -n "$HOST_MAC" ] && HOST_ARGS+=("-mac=${HOST_MAC//:/-}")
 [ -n "$HOST_BUILD" ] && HOST_ARGS+=("-build=${HOST_BUILD}")
 [ -n "$HOST_SERIAL" ] && HOST_ARGS+=("-hostsn=${HOST_SERIAL}")
 [ -n "$GUEST_SERIAL" ] && HOST_ARGS+=("-guestsn=${GUEST_SERIAL}")