diff --git a/agents/plugins/mk_postgres.py b/agents/plugins/mk_postgres.py
index 0a40a6483b6..09df3968c0a 100755
--- a/agents/plugins/mk_postgres.py
+++ b/agents/plugins/mk_postgres.py
@@ -784,7 +784,8 @@ def _run_sql_as_db_user(
         # type: (str, str, str, bool, bool) -> str
         base_cmd_list = [
             "su",
-            "-",
+            "-s",
+            "/bin/sh",
             self.db_user,
             "-c",
             r"""PGPASSFILE=%s %s -X %s -A0 -F'%s' -f %s""",