diff --git a/postgres-backup/app/backup.sh b/postgres-backup/app/backup.sh
index b0764c5..2f3c096 100644
--- a/postgres-backup/app/backup.sh
+++ b/postgres-backup/app/backup.sh
@@ -20,8 +20,7 @@ function backup_init() {
 function backup_db_postgresql() {
   echo "backup postgresql database"
 
-  pg_dump -Fc -h "${POSTGRES_HOST}" -p "${POSTGRES_PORT}" -d "${POSTGRES_DB}" -U "${POSTGRES_USER}" -f "${BACKUP_FILE_DB_POSTGRESQL}"
-  if [[ ! pg_dump ]]; then
+  if ! pg_dump -Fc -h "${POSTGRES_HOST}" -p "${POSTGRES_PORT}" -d "${POSTGRES_DB}" -U "${POSTGRES_USER}" -f "${BACKUP_FILE_DB_POSTGRESQL}"; then
     echo "backup postgresql database failed"
 
     exit 1