diff --git a/apps/emqx_authn/src/simple_authn/emqx_authn_mysql.erl b/apps/emqx_authn/src/simple_authn/emqx_authn_mysql.erl
index 065e951c5..98d515310 100644
--- a/apps/emqx_authn/src/simple_authn/emqx_authn_mysql.erl
+++ b/apps/emqx_authn/src/simple_authn/emqx_authn_mysql.erl
@@ -145,7 +145,7 @@ parse_query(Query) ->
     case re:run(Query, ?RE_PLACEHOLDER, [global, {capture, all, binary}]) of
         {match, Captured} ->
             PlaceHolders = [PlaceHolder || [PlaceHolder] <- Captured],
-            NQuery = re:replace(Query, "'\\$\\{[a-z0-9\\-]+\\}'", "?", [global, {return, binary}]),
+            NQuery = re:replace(Query, ?RE_PLACEHOLDER, "?", [global, {return, binary}]),
             {NQuery, PlaceHolders};
         nomatch ->
             {Query, []}
diff --git a/apps/emqx_authn/src/simple_authn/emqx_authn_pgsql.erl b/apps/emqx_authn/src/simple_authn/emqx_authn_pgsql.erl
index 4086f4b22..2b8c9b391 100644
--- a/apps/emqx_authn/src/simple_authn/emqx_authn_pgsql.erl
+++ b/apps/emqx_authn/src/simple_authn/emqx_authn_pgsql.erl
@@ -137,7 +137,7 @@ parse_query(Query) ->
             PlaceHolders = [PlaceHolder || [PlaceHolder] <- Captured],
             Replacements = ["$" ++ integer_to_list(I) || I <- lists:seq(1, length(Captured))],
             NQuery = lists:foldl(fun({PlaceHolder, Replacement}, Query0) ->
-                                     re:replace(Query0, <<"'\\", PlaceHolder/binary, "'">>, Replacement, [{return, binary}])
+                                     re:replace(Query0, PlaceHolder, Replacement, [{return, binary}])
                                  end, Query, lists:zip(PlaceHolders, Replacements)),
             {NQuery, PlaceHolders};
         nomatch ->