diff --git a/scripts/check-image.sh b/scripts/check-image.sh
index de1a10f..638e137 100755
--- a/scripts/check-image.sh
+++ b/scripts/check-image.sh
@@ -4,6 +4,9 @@ set -o errexit
 set -o nounset
 set -o pipefail
 
+DEBUG="${DEBUG:-}"
+INCREMENTAL="${INCREMENTAL:-}"
+
 declare -A DOMAIN_MAP=()
 
 for line in $(cat ./domain.txt); do
@@ -58,7 +61,7 @@ for line in $(cat ./mirror.txt); do
     domain="${line%%/*}"
     new_image=$(echo "${line}" | sed "s/^${domain}/${DOMAIN_MAP["${domain}"]}/g")
     echo "Diff image ${line} ${new_image}"
-    DEBUG=true INCREMENTAL=true EXCLUDED="${exclude}" ./scripts/diff-image.sh "${line}" "${new_image}" 2>&1 | tee -a "${LOGFILE}" || {
+    DEBUG="${DEBUG}" INCREMENTAL="${INCREMENTAL}" EXCLUDED="${exclude}" ./scripts/diff-image.sh "${line}" "${new_image}" 2>&1 | tee -a "${LOGFILE}" || {
         echo "Error: diff image ${line} ${new_image}"
     }
 done