diff --git a/lib/csv-diff/algorithm.rb b/lib/csv-diff/algorithm.rb
index 6b5db2a..3d7817c 100644
--- a/lib/csv-diff/algorithm.rb
+++ b/lib/csv-diff/algorithm.rb
@@ -37,9 +37,7 @@ def sibling_position=(pos_idx)
             def [](key)
                 case key
                 when :action
-                    a = diff_type.to_s
-                    a[0] = a[0].upcase
-                    a
+                    diff_type.to_s.capitalize
                 when :row
                     @row
                 when :sibling_position