diff --git a/lib/writeexcel/workbook.rb b/lib/writeexcel/workbook.rb
index <HASH>..<HASH> 100644
--- a/lib/writeexcel/workbook.rb
+++ b/lib/writeexcel/workbook.rb
@@ -78,7 +78,6 @@ class Workbook < BIFFWriter
     @biffsize              = 0
     @sheet_count           = 0
     @chart_count           = 0
-    @url_format            = ''
     @codepage              = 0x04E4
     @country               = 1
     @worksheets            = []
* delete meaningless @url_format value set.