diff --git a/Rakefile b/Rakefile
index f16f94b..0eed3cb 100644
--- a/Rakefile
+++ b/Rakefile
@@ -16,7 +16,7 @@ def pad(array)
   array.each do |row|
     i = 0
     row.each do |col|
-      max[i] = [max[i] || 0, col.length].max
+      max[i] = [max[i] || 0, col.bytesize].max
       i += 1
     end
   end
@@ -24,7 +24,7 @@ def pad(array)
   array.each do |row|
     i = 0
     row.each do |col|
-      col << " " * (max[i] - col.length)
+      col << " " * (max[i] - col.bytesize)
       i += 1
     end
   end
diff --git a/lib/mini_mime.rb b/lib/mini_mime.rb
index 8055fdb..ffec0f3 100644
--- a/lib/mini_mime.rb
+++ b/lib/mini_mime.rb
@@ -124,7 +124,7 @@ def initialize(path, sort_order)
         @path = path
         @file = PReadFile.new(@path)
 
-        @row_length = @file.readline("\n").length
+        @row_length = @file.readline("\n").bytesize
         @file_length = File.size(@path)
         @rows = @file_length / @row_length