diff --git a/src/util/prefixed_io.cr b/src/util/prefixed_io.cr
index 15ddd71..10dfb6d 100644
--- a/src/util/prefixed_io.cr
+++ b/src/util/prefixed_io.cr
@@ -6,9 +6,10 @@ class PrefixedIO < IO
   end
 
   def write(slice : Bytes) : Nil
-    content = String.new(slice)
-    content.lines.each do |line|
-      @io << @prefix << "#{line}\n"
+    @io.print @prefix
+    slice.each do |byte|
+      @io.write_byte byte
+      @io.print @prefix if 10 == byte
     end
   end
 end