diff --git a/tools/deploy-qemu b/tools/deploy-qemu
index 7866337a3..301ce45f6 100755
--- a/tools/deploy-qemu
+++ b/tools/deploy-qemu
@@ -17,7 +17,7 @@
 
 set -euo pipefail
 
-if [[ -z "$1" || -z "$2" ]]; then
+if [[ "$#" != 2 ]]; then
   echo "usage: $0 IMAGE USERDATA"
   exit 1
 fi