diff --git a/lib/money/currency.rb b/lib/money/currency.rb
index f8b2a1d5df..db4f7062ef 100644
--- a/lib/money/currency.rb
+++ b/lib/money/currency.rb
@@ -83,8 +83,8 @@ def find(id)
       def find_by_iso_numeric(num)
         num = num.to_s.rjust(3, '0')
         return if num.empty?
-        id, _ = self.table.find { |key, currency| currency[:iso_numeric] == num }
-        new(id)
+        id = iso_numeric_index[num]
+        new(id) if id
       rescue UnknownCurrency
         nil
       end
@@ -215,6 +215,12 @@ def reset!
       end
 
       private
+            
+      def iso_numeric_index
+        @iso_numeric_index ||= table.each_with_object({}) do |(id, attrs), index|
+          index[attrs[:iso_numeric]] = id
+        end
+      end
 
       def stringify_keys
         table.keys.each_with_object(Set.new) { |k, set| set.add(k.to_s.downcase) }