diff --git a/src/Parsers/Kusto/ParserKQLQuery.cpp b/src/Parsers/Kusto/ParserKQLQuery.cpp
index 29b26b4e3fed..a54a2b0eda9a 100644
--- a/src/Parsers/Kusto/ParserKQLQuery.cpp
+++ b/src/Parsers/Kusto/ParserKQLQuery.cpp
@@ -416,8 +416,9 @@ bool ParserKQLQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
                     ParserToken s_dash(TokenType::Minus);
                     if (s_dash.ignore(pos, expected))
                     {
-                        String tmp_op(op_pos_begin->begin, pos->end);
-                        kql_operator = tmp_op;
+                        if (!isValidKQLPos(pos))
+                            return false;
+                        kql_operator = String(op_pos_begin->begin, pos->end);
                     }
                     else
                         --pos;
diff --git a/tests/queries/0_stateless/02366_kql_mvexpand.sql b/tests/queries/0_stateless/02366_kql_mvexpand.sql
index e77986096463..af336a196387 100644
--- a/tests/queries/0_stateless/02366_kql_mvexpand.sql
+++ b/tests/queries/0_stateless/02366_kql_mvexpand.sql
@@ -33,3 +33,7 @@ print '-- mv_expand_test_table | mv-expand with_itemindex=index c,d to typeof(bo
 mv_expand_test_table | mv-expand with_itemindex=index c,d to typeof(bool);
 print '-- mv_expand_test_table | mv-expand c to typeof(bool) --';
 mv_expand_test_table | mv-expand c to typeof(bool);
+SET max_query_size = 28;
+SET dialect='kusto';
+mv_expand_test_table | mv-expand c, d; -- { serverError SYNTAX_ERROR }
+SET max_query_size=262144;