diff --git a/ext/numeric.rb b/ext/numeric.rb
index 3f385fa2..084e5c29 100644
--- a/ext/numeric.rb
+++ b/ext/numeric.rb
@@ -31,7 +31,7 @@ class Numeric
   end
 
   def to_comma_separated
-    self.to_s.chars.to_a.reverse.each_slice(3).map(&:join).join(",").reverse
+    self.to_i.to_s.chars.to_a.reverse.each_slice(3).map(&:join).join(",").reverse
   end
 
   def format_large_number