diff --git a/lib/tty/table/orientation/vertical.rb b/lib/tty/table/orientation/vertical.rb
index b1d95b2..52b6487 100644
--- a/lib/tty/table/orientation/vertical.rb
+++ b/lib/tty/table/orientation/vertical.rb
@@ -26,7 +26,7 @@ def slice(table)
           header    = table.header
           rows_size = table.rows_size
 
-          head = header ? header : (0..rows_size).map { |n| (n + 1).to_s }
+          head = header ? header : (1..table.columns_count).map(&:to_s)
 
           (0...rows_size).reduce([]) do |array, index|
             array + head.zip(table.rows[index]).map { |row| table.to_row(row) }