diff --git a/dbms/src/Columns/getLeastSuperColumn.cpp b/dbms/src/Columns/getLeastSuperColumn.cpp
index 11c5b1b58fdeb4a39a6d73e7e5501b190d123874..663337b6f87980812b8fbf44406fe2b9aa4536e4 100644
--- a/dbms/src/Columns/getLeastSuperColumn.cpp
+++ b/dbms/src/Columns/getLeastSuperColumn.cpp
@@ -18,7 +18,7 @@ static bool sameConstants(const IColumn & a, const IColumn & b)
     return assert_cast<const ColumnConst &>(a).getField() == assert_cast<const ColumnConst &>(b).getField();
 }
 
-ColumnWithTypeAndName getLeastSuperColumn(std::vector<const ColumnWithTypeAndName *> columns)
+ColumnWithTypeAndName getLeastSuperColumn(const std::vector<const ColumnWithTypeAndName *> & columns)
 {
     if (columns.empty())
         throw Exception("Logical error: no src columns for supercolumn", ErrorCodes::LOGICAL_ERROR);
diff --git a/dbms/src/Columns/getLeastSuperColumn.h b/dbms/src/Columns/getLeastSuperColumn.h
index d761de29a93e5d558c6d96f7ecec1543458eae0b..cd8dc53a895b0c2af9e4ceb626d2e8a99e8d23aa 100644
--- a/dbms/src/Columns/getLeastSuperColumn.h
+++ b/dbms/src/Columns/getLeastSuperColumn.h
@@ -7,6 +7,6 @@ namespace DB
 {
 
 /// getLeastSupertype + related column changes
-ColumnWithTypeAndName getLeastSuperColumn(std::vector<const ColumnWithTypeAndName *> columns);
+ColumnWithTypeAndName getLeastSuperColumn(const std::vector<const ColumnWithTypeAndName *> & columns);
 
 }
diff --git a/dbms/src/Interpreters/InterpreterSelectWithUnionQuery.cpp b/dbms/src/Interpreters/InterpreterSelectWithUnionQuery.cpp
index 93916db4a1de4311e734bec37dbd83339c841899..2d7fde72875e6ad836cf0eb7386133455dd57587 100644
--- a/dbms/src/Interpreters/InterpreterSelectWithUnionQuery.cpp
+++ b/dbms/src/Interpreters/InterpreterSelectWithUnionQuery.cpp
@@ -126,7 +126,7 @@ Block InterpreterSelectWithUnionQuery::getCommonHeaderForUnion(const Blocks & he
                             ErrorCodes::UNION_ALL_RESULT_STRUCTURES_MISMATCH);
     }
 
-    std::vector<const ColumnWithTypeAndName *> columns(num_columns);
+    std::vector<const ColumnWithTypeAndName *> columns(num_selects);
 
     for (size_t column_num = 0; column_num < num_columns; ++column_num)
     {