diff --git a/aarch64/run_qemu.sh b/aarch64/run_qemu.sh
index 19b97d4..ed99af3 100755
--- a/aarch64/run_qemu.sh
+++ b/aarch64/run_qemu.sh
@@ -86,7 +86,7 @@
 }
 
 function hex() {
-	printf '0x%x\n' $1
+	printf "%${2-#}x\n" $1
 }
 
 function template_overlay() {