diff --git a/postgres-backup/app/backup.sh b/postgres-backup/app/backup.sh
index 289a04a..b0764c5 100644
--- a/postgres-backup/app/backup.sh
+++ b/postgres-backup/app/backup.sh
@@ -1,5 +1,6 @@
 #!/bin/bash
 
+# shellcheck source=/dev/null
 . /app/includes.sh
 
 function clear_dir() {
@@ -20,7 +21,7 @@ function backup_db_postgresql() {
   echo "backup postgresql database"
 
   pg_dump -Fc -h "${POSTGRES_HOST}" -p "${POSTGRES_PORT}" -d "${POSTGRES_DB}" -U "${POSTGRES_USER}" -f "${BACKUP_FILE_DB_POSTGRESQL}"
-  if [[ $? != 0 ]]; then
+  if [[ ! pg_dump ]]; then
     echo "backup postgresql database failed"
 
     exit 1