diff --git a/guides/rails_guides/levenshtein.rb b/guides/rails_guides/levenshtein.rb
index 36183fd321..049f633258 100644
--- a/guides/rails_guides/levenshtein.rb
+++ b/guides/rails_guides/levenshtein.rb
@@ -14,10 +14,13 @@ module RailsGuides
       d = (0..m).to_a
       x = nil
 
-      str1.each_char.each_with_index do |char1,i|
+      # avoid duplicating an enumerable object in the loop
+      str2_codepoint_enumerable = str2.each_codepoint
+
+      str1.each_codepoint.with_index do |char1, i|
         e = i+1
 
-        str2.each_char.each_with_index do |char2,j|
+        str2_codepoint_enumerable.with_index do |char2, j|
           cost = (char1 == char2) ? 0 : 1
           x = [
                d[j+1] + 1, # insertion
diff --git a/railties/lib/rails/generators.rb b/railties/lib/rails/generators.rb
index 341291f08b..a7da92168d 100644
--- a/railties/lib/rails/generators.rb
+++ b/railties/lib/rails/generators.rb
@@ -267,10 +267,13 @@ module Rails
         d = (0..m).to_a
         x = nil
 
-        str1.each_char.each_with_index do |char1,i|
+        # avoid duplicating an enumerable object in the loop
+        str2_codepoint_enumerable = str2.each_codepoint
+
+        str1.each_codepoint.with_index do |char1, i|
           e = i+1
 
-          str2.each_char.each_with_index do |char2,j|
+          str2_codepoint_enumerable.with_index do |char2, j|
             cost = (char1 == char2) ? 0 : 1
             x = [
                  d[j+1] + 1, # insertion