diff --git a/lib/puppet/file_system/file19.rb b/lib/puppet/file_system/file19.rb
index 63df6f7e9..8872ba6fc 100644
--- a/lib/puppet/file_system/file19.rb
+++ b/lib/puppet/file_system/file19.rb
@@ -1,25 +1,46 @@
 class Puppet::FileSystem::File19 < Puppet::FileSystem::FileImpl
   def binread(path)
     path.binread
   end
 
   # Provide an encoding agnostic version of compare_stream
   #
   # The FileUtils implementation in Ruby 2.0+ was modified in a manner where
   # it cannot properly compare File and StringIO instances. To sidestep that
   # issue this method reimplements the faster 2.0 version that will correctly
   # compare binary File and StringIO streams.
   def compare_stream(path, stream)
     open(path, 0, 'rb') do |this|
-      bsize = FileUtils.send(:fu_stream_blksize, this, stream)
+      bsize = stream_blksize(this, stream)
       sa = "".force_encoding('ASCII-8BIT')
       sb = "".force_encoding('ASCII-8BIT')
       begin
         this.read(bsize, sa)
         stream.read(bsize, sb)
         return true if sa.empty? && sb.empty?
       end while sa == sb
       false
     end
   end
+
+  private
+  def stream_blksize(*streams)
+    streams.each do |s|
+      next unless s.respond_to?(:stat)
+      size = blksize(s.stat)
+      return size if size
+    end
+    default_blksize()
+  end
+
+  def blksize(st)
+    s = st.blksize
+    return nil unless s
+    return nil if s == 0
+    s
+  end
+
+  def default_blksize
+    1024
+  end
 end