diff --git a/script/entrypoint.sh b/script/entrypoint.sh
index 166f4837..68e1b146 100755
--- a/script/entrypoint.sh
+++ b/script/entrypoint.sh
@@ -52,7 +52,7 @@ if [ "$AIRFLOW__CORE__EXECUTOR" != "SequentialExecutor" ]; then
     : "${POSTGRES_USER:="airflow"}"
     : "${POSTGRES_PASSWORD:="airflow"}"
     : "${POSTGRES_DB:="airflow"}"
-    : "${POSTGRES_EXTRAS:-""}"
+    : "${POSTGRES_EXTRAS:=""}"
 
     AIRFLOW__CORE__SQL_ALCHEMY_CONN="postgresql+psycopg2://${POSTGRES_USER}:${POSTGRES_PASSWORD}@${POSTGRES_HOST}:${POSTGRES_PORT}/${POSTGRES_DB}${POSTGRES_EXTRAS}"
     export AIRFLOW__CORE__SQL_ALCHEMY_CONN