diff --git a/dbms/src/Common/Macros.cpp b/dbms/src/Common/Macros.cpp
index 3681a544388..5d111abb0c6 100644
--- a/dbms/src/Common/Macros.cpp
+++ b/dbms/src/Common/Macros.cpp
@@ -69,13 +69,14 @@ String Macros::expand(const String & s, size_t level) const
     return expand(res, level + 1);
 }
 
-Names Macros::expand(const Names & s, size_t level) const
+Names Macros::expand(const Names & source_names, size_t level) const
 {
-    Names names;
+    Names result_names;
+    result_names.reserve(source_names.size());
 
-    for (const String name : s)
-        names.push_back(expand(name, level));
+    for (const String & name : source_names)
+        result_names.push_back(expand(name, level));
     
-    return names;
+    return result_names;
 }
 }