diff --git a/src/gapbs/disk-image/gapbs/gapbs.json b/src/gapbs/disk-image/gapbs/gapbs.json
index b152761..b5e7a65 100644
--- a/src/gapbs/disk-image/gapbs/gapbs.json
+++ b/src/gapbs/disk-image/gapbs/gapbs.json
@@ -32,8 +32,7 @@
             ],
             "headless": "{{ user `headless` }}",
             "http_directory": "http",
-            "iso_checksum": "{{ user `iso_checksum` }}",
-            "iso_checksum_type": "{{ user `iso_checksum_type` }}",
+            "iso_checksum": "{{ user `iso_checksum_type` }}:{{ user `iso_checksum` }}",
             "iso_urls": [ "{{ user `iso_url` }}" ],
             "memory": "{{ user `vm_memory`}}",
             "output_directory": "{{ user `image_name` }}-image",