diff --git a/scripts/qemustart b/scripts/qemustart
index 5af93b9aed..5bb8ca5f3a 100755
--- a/scripts/qemustart
+++ b/scripts/qemustart
@@ -113,7 +113,7 @@ EOF
 }
 
 rand_mac() {
-	hexdump -n 3 -e '"52:54:00:" 2/1 "%02x:" 1/1 "%02x"' /dev/urandom
+	hexdump -n 3 -e '"52:54:00" 3/1 ":%02x"' /dev/urandom
 }
 
 parse_args() {