diff --git a/lib/oxcelix/numformats.rb b/lib/oxcelix/numformats.rb
index <HASH>..<HASH> 100644
--- a/lib/oxcelix/numformats.rb
+++ b/lib/oxcelix/numformats.rb
@@ -10,7 +10,7 @@ module Oxcelix
       # Convert the temporary format array (the collection of non-default number formatting strings defined in the excel sheet in use)
       # to a series of hashes containing an id, an excel format string, a converted format string and an object class the format is
       # interpreted on.
-      def add fmtary
+      def add_custom_formats fmtary
         fmtary.each do |x|
           if x[:formatCode] =~ /[#0%\?]/
             ostring = numeric x[:formatCode]
diff --git a/lib/oxcelix/workbook.rb b/lib/oxcelix/workbook.rb
index <HASH>..<HASH> 100644
--- a/lib/oxcelix/workbook.rb
+++ b/lib/oxcelix/workbook.rb
@@ -72,7 +72,7 @@ module Oxcelix
       end
 
       styles.temparray.sort_by!{|st| st[:numFmtId].to_i}
-      add styles.temparray
+      add_custom_formats styles.temparray
       styles.styleary.map!{|s| Numformats::Formatarray[s.to_i][:id].to_i}
 
       @sheets.each do |x|
Renamed add to add_custom_formats