diff --git a/spec/payload_spec.cr b/spec/payload_spec.cr
index f4eb6cc..e6c18c7 100644
--- a/spec/payload_spec.cr
+++ b/spec/payload_spec.cr
@@ -1,6 +1,6 @@
 require "./spec_helper"
 
-class NonPositionIO < ::IO
+class DummyIO < ::IO
   def initialize(@data : Bytes)
   end
 
@@ -31,60 +31,48 @@ describe MQTT::Protocol::Payload do
     it "should return true for two BytePayload with same bytes" do
       one = MQTT::Protocol::BytesPayload.new("foo".to_slice)
       two = MQTT::Protocol::BytesPayload.new("foo".to_slice)
-
       (one == two).should be_true
     end
 
     it "should return false for two BytePayload with different bytes" do
       one = MQTT::Protocol::BytesPayload.new("foo".to_slice)
       two = MQTT::Protocol::BytesPayload.new("bar".to_slice)
-
       (one == two).should be_false
     end
 
     it "should return true for two IOPayload with same content" do
       io_one = IO::Memory.new("foo".to_slice)
       io_two = IO::Memory.new("foo".to_slice)
-
       io_one.rewind
       io_two.rewind
-
       one = MQTT::Protocol::IOPayload.new(io_one, 3)
       two = MQTT::Protocol::IOPayload.new(io_two, 3)
-
       (one == two).should be_true
     end
 
     it "should return false for two IOPayload with different content" do
       io_one = IO::Memory.new("foo".to_slice)
       io_two = IO::Memory.new("bar".to_slice)
-
       io_one.rewind
       io_two.rewind
-
       one = MQTT::Protocol::IOPayload.new(io_one, 3)
       two = MQTT::Protocol::IOPayload.new(io_two, 3)
-
       (one == two).should be_false
     end
 
     it "should return true for one BytesPayload and one IOPayload with same content" do
       io_two = IO::Memory.new("foo".to_slice)
       io_two.rewind
-
       one = MQTT::Protocol::BytesPayload.new("foo".to_slice)
       two = MQTT::Protocol::IOPayload.new(io_two, 3)
-
       (one == two).should be_true
     end
 
     it "should return false for one BytesPayload and one IOPayload with different content" do
       io_two = IO::Memory.new("bar".to_slice)
       io_two.rewind
-
       one = MQTT::Protocol::BytesPayload.new("foo".to_slice)
       two = MQTT::Protocol::IOPayload.new(io_two, 3)
-
       (one == two).should be_false
     end
   end
@@ -94,46 +82,49 @@ describe MQTT::Protocol::Payload do
       it "should peek if possible" do
         io = IO::Memory.new("foo".to_slice)
         io.rewind
-
         obj = MQTT::Protocol::IOPayload.new(io, 3)
-        obj.to_slice
-
+        obj.to_slice.should eq "foo".to_slice
         obj.@data.should be_nil
       end
 
       it "should copy data if peek isn't possible" do
-        io = NonPositionIO.new("foo".to_slice)
-
+        io = DummyIO.new("foo".to_slice)
         obj = MQTT::Protocol::IOPayload.new(io, 3)
-        obj.to_slice
-
+        obj.to_slice.should eq "foo".to_slice
         obj.@data.should eq "foo".to_slice
       end
     end
 
     describe "#to_io" do
-      it "should not affect position if io support pos/pos=" do
-        io = IO::Memory.new("foo".to_slice)
-        io.rewind
+      it "should not affect position if io is FileDescriptor" do
+        File.open(File.tempfile.path, "w+") do |io|
+          io.write "foo".to_slice
+          io.rewind
+          obj = MQTT::Protocol::IOPayload.new(io, 3)
+          dst = IO::Memory.new
+          obj.to_io(dst)
+          obj.@data.should be_nil
+          obj.@io.pos.should eq 0
+          dst.to_slice.should eq "foo".to_slice
+        end
+      end
 
+      it "should not copy data if io is Memory" do
+        io = ::IO::Memory.new("foo".to_slice)
         obj = MQTT::Protocol::IOPayload.new(io, 3)
-
         dst = IO::Memory.new
         obj.to_io(dst)
-
         obj.@data.should be_nil
-        obj.@io.pos.should eq 0
+        dst.to_slice.should eq "foo".to_slice
       end
 
-      it "should copy data if io doesn't support pos/pos=" do
-        io = NonPositionIO.new("foo".to_slice)
-
+      it "should copy data if io is other than Memory or FileDescriptor" do
+        io = DummyIO.new("foo".to_slice)
         obj = MQTT::Protocol::IOPayload.new(io, 3)
-
         dst = IO::Memory.new
         obj.to_io(dst)
-
         obj.@data.should eq "foo".to_slice
+        dst.to_slice.should eq "foo".to_slice
       end
     end
   end