diff --git a/lib/erl/src/thrift_binary_protocol.erl b/lib/erl/src/thrift_binary_protocol.erl
index 00300ba..fcb072b 100644
--- a/lib/erl/src/thrift_binary_protocol.erl
+++ b/lib/erl/src/thrift_binary_protocol.erl
@@ -60,79 +60,81 @@
     parse_options(Rest, State#binary_protocol{strict_write=Bool}).
 
 
-flush_transport(#binary_protocol{transport = Transport}) ->
-    thrift_transport:flush(Transport).
+flush_transport(This = #binary_protocol{transport = Transport}) ->
+    Result = thrift_transport:flush(Transport),
+    {This, Result}.
 
-close_transport(#binary_protocol{transport = Transport}) ->
-    thrift_transport:close(Transport).
+close_transport(This = #binary_protocol{transport = Transport}) ->
+    Result = thrift_transport:close(Transport),
+    {This, Result}.
 
 %%%
 %%% instance methods
 %%%
 
-write(This, #protocol_message_begin{
+write(This0, #protocol_message_begin{
         name = Name,
         type = Type,
         seqid = Seqid}) ->
-    case This#binary_protocol.strict_write of
+    case This0#binary_protocol.strict_write of
         true ->
-            write(This, {i32, ?VERSION_1 bor Type}),
-            write(This, {string, Name}),
-            write(This, {i32, Seqid});
+            {This1, ok} = write(This0, {i32, ?VERSION_1 bor Type}),
+            {This2, ok} = write(This1, {string, Name}),
+            {This3, ok} = write(This2, {i32, Seqid}),
+            {This3, ok};
         false ->
-            write(This, {string, Name}),
-            write(This, {byte, Type}),
-            write(This, {i32, Seqid})
-    end,
-    ok;
+            {This1, ok} = write(This0, {string, Name}),
+            {This2, ok} = write(This1, {byte, Type}),
+            {This3, ok} = write(This2, {i32, Seqid}),
+            {This3, ok}
+    end;
 
-write(This, message_end) -> ok;
+write(This, message_end) -> {This, ok};
 
-write(This, #protocol_field_begin{
+write(This0, #protocol_field_begin{
        name = _Name,
        type = Type,
        id = Id}) ->
-    write(This, {byte, Type}),
-    write(This, {i16, Id}),
-    ok;
+    {This1, ok} = write(This0, {byte, Type}),
+    {This2, ok} = write(This1, {i16, Id}),
+    {This2, ok};
 
 write(This, field_stop) ->
-    write(This, {byte, ?tType_STOP}),
-    ok;
+    write(This, {byte, ?tType_STOP});
 
-write(This, field_end) -> ok;
+write(This, field_end) -> {This, ok};
 
-write(This, #protocol_map_begin{
+write(This0, #protocol_map_begin{
        ktype = Ktype,
        vtype = Vtype,
        size = Size}) ->
-    write(This, {byte, Ktype}),
-    write(This, {byte, Vtype}),
-    write(This, {i32, Size}),
-    ok;
+    {This1, ok} = write(This0, {byte, Ktype}),
+    {This2, ok} = write(This1, {byte, Vtype}),
+    {This3, ok} = write(This2, {i32, Size}),
+    {This3, ok};
 
-write(This, map_end) -> ok;
+write(This, map_end) -> {This, ok};
 
-write(This, #protocol_list_begin{
+write(This0, #protocol_list_begin{
         etype = Etype,
         size = Size}) ->
-    write(This, {byte, Etype}),
-    write(This, {i32, Size}),
-    ok;
+    {This1, ok} = write(This0, {byte, Etype}),
+    {This2, ok} = write(This1, {i32, Size}),
+    {This2, ok};
 
-write(This, list_end) -> ok;
+write(This, list_end) -> {This, ok};
 
-write(This, #protocol_set_begin{
+write(This0, #protocol_set_begin{
         etype = Etype,
         size = Size}) ->
-    write(This, {byte, Etype}),
-    write(This, {i32, Size}),
-    ok;
+    {This1, ok} = write(This0, {byte, Etype}),
+    {This2, ok} = write(This1, {i32, Size}),
+    {This2, ok};
 
-write(This, set_end) -> ok;
+write(This, set_end) -> {This, ok};
 
-write(This, #protocol_struct_begin{}) -> ok;
-write(This, struct_end) -> ok;
+write(This, #protocol_struct_begin{}) -> {This, ok};
+write(This, struct_end) -> {This, ok};
 
 write(This, {bool, true})  -> write(This, {byte, 1});
 write(This, {bool, false}) -> write(This, {byte, 0});
@@ -152,153 +154,166 @@
 write(This, {double, Double}) ->
     write(This, <<Double:64/big-signed-float>>);
 
-write(This, {string, Str}) when is_list(Str) ->
-    write(This, {i32, length(Str)}),
-    write(This, list_to_binary(Str));
+write(This0, {string, Str}) when is_list(Str) ->
+    {This1, ok} = write(This0, {i32, length(Str)}),
+    {This2, ok} = write(This1, list_to_binary(Str)),
+    {This2, ok};
 
-write(This, {string, Bin}) when is_binary(Bin) ->
-    write(This, {i32, size(Bin)}),
-    write(This, Bin);
+write(This0, {string, Bin}) when is_binary(Bin) ->
+    {This1, ok} = write(This0, {i32, size(Bin)}),
+    {This2, ok} = write(This1, Bin),
+    {This2, ok};
 
 %% Data :: iolist()
-write(This, Data) ->
-    thrift_transport:write(This#binary_protocol.transport, Data).
+write(This = #binary_protocol{transport = Trans}, Data) ->
+    Result = thrift_transport:write(Trans, Data),
+    {This, Result}.
 
 %%
 
-read(This, message_begin) ->
-    case read(This, ui32) of
+read(This0, message_begin) ->
+    {This1, Initial} = read(This0, ui32),
+    case Initial of
         {ok, Sz} when Sz band ?VERSION_MASK =:= ?VERSION_1 ->
             %% we're at version 1
-            {ok, Name}  = read(This, string),
-            Type        = Sz band ?TYPE_MASK,
-            {ok, SeqId} = read(This, i32),
-            #protocol_message_begin{name  = binary_to_list(Name),
-                                    type  = Type,
-                                    seqid = SeqId};
+            {This2, {ok, Name}}  = read(This1, string),
+            {This3, {ok, SeqId}} = read(This2, i32),
+            Type                 = Sz band ?TYPE_MASK,
+            {This3, #protocol_message_begin{name  = binary_to_list(Name),
+                                            type  = Type,
+                                            seqid = SeqId}};
 
         {ok, Sz} when Sz < 0 ->
             %% there's a version number but it's unexpected
-            {error, {bad_binary_protocol_version, Sz}};
+            {This1, {error, {bad_binary_protocol_version, Sz}}};
 
-        {ok, Sz} when This#binary_protocol.strict_read =:= true ->
+        {ok, Sz} when This1#binary_protocol.strict_read =:= true ->
             %% strict_read is true and there's no version header; that's an error
-            {error, no_binary_protocol_version};
+            {This1, {error, no_binary_protocol_version}};
 
-        {ok, Sz} when This#binary_protocol.strict_read =:= false ->
+        {ok, Sz} when This1#binary_protocol.strict_read =:= false ->
             %% strict_read is false, so just read the old way
-            {ok, Name}  = read_data(This, Sz),
-            {ok, Type}  = read(This, byte),
-            {ok, SeqId} = read(This, i32),
-            #protocol_message_begin{name  = binary_to_list(Name),
-                                    type  = Type,
-                                    seqid = SeqId};
+            {This2, {ok, Name}}  = read_data(This1, Sz),
+            {This3, {ok, Type}}  = read(This2, byte),
+            {This4, {ok, SeqId}} = read(This3, i32),
+            {This4, #protocol_message_begin{name  = binary_to_list(Name),
+                                            type  = Type,
+                                            seqid = SeqId}};
 
-        Err = {error, closed} -> Err;
-        Err = {error, timeout}-> Err;
-        Err = {error, ebadf}  -> Err
+        Else ->
+            {This1, Else}
     end;
 
-read(This, message_end) -> ok;
+read(This, message_end) -> {This, ok};
 
-read(This, struct_begin) -> ok;
-read(This, struct_end) -> ok;
+read(This, struct_begin) -> {This, ok};
+read(This, struct_end) -> {This, ok};
 
-read(This, field_begin) ->
-    case read(This, byte) of
+read(This0, field_begin) ->
+    {This1, Result} = read(This0, byte),
+    case Result of
         {ok, Type = ?tType_STOP} ->
-            #protocol_field_begin{type = Type};
+            {This1, #protocol_field_begin{type = Type}};
         {ok, Type} ->
-            {ok, Id} = read(This, i16),
-            #protocol_field_begin{type = Type,
-                                  id = Id}
+            {This2, {ok, Id}} = read(This1, i16),
+            {This2, #protocol_field_begin{type = Type,
+                                          id = Id}}
     end;
 
-read(This, field_end) -> ok;
+read(This, field_end) -> {This, ok};
 
-read(This, map_begin) ->
-    {ok, Ktype} = read(This, byte),
-    {ok, Vtype} = read(This, byte),
-    {ok, Size}  = read(This, i32),
-    #protocol_map_begin{ktype = Ktype,
-                        vtype = Vtype,
-                        size = Size};
-read(This, map_end) -> ok;
+read(This0, map_begin) ->
+    {This1, {ok, Ktype}} = read(This0, byte),
+    {This2, {ok, Vtype}} = read(This1, byte),
+    {This3, {ok, Size}}  = read(This2, i32),
+    {This3, #protocol_map_begin{ktype = Ktype,
+                                vtype = Vtype,
+                                size = Size}};
+read(This, map_end) -> {This, ok};
 
-read(This, list_begin) ->
-    {ok, Etype} = read(This, byte),
-    {ok, Size}  = read(This, i32),
-    #protocol_list_begin{etype = Etype,
-                         size = Size};
-read(This, list_end) -> ok;
+read(This0, list_begin) ->
+    {This1, {ok, Etype}} = read(This0, byte),
+    {This2, {ok, Size}}  = read(This1, i32),
+    {This2, #protocol_list_begin{etype = Etype,
+                                 size = Size}};
+read(This, list_end) -> {This, ok};
 
-read(This, set_begin) ->
-    {ok, Etype} = read(This, byte),
-    {ok, Size}  = read(This, i32),
-    #protocol_set_begin{etype = Etype,
-                        size = Size};
-read(This, set_end) -> ok;
+read(This0, set_begin) ->
+    {This1, {ok, Etype}} = read(This0, byte),
+    {This2, {ok, Size}}  = read(This1, i32),
+    {This2, #protocol_set_begin{etype = Etype,
+                                 size = Size}};
+read(This, set_end) -> {This, ok};
 
-read(This, field_stop) ->
-    {ok, ?tType_STOP} =  read(This, byte),
-    ok;
+read(This0, field_stop) ->
+    {This1, {ok, ?tType_STOP}} = read(This0, byte),
+    {This1, ok};
 
 %%
 
-read(This, bool) ->
-    case read(This, byte) of
-        {ok, Byte} -> {ok, Byte /= 0};
-        Else -> Else
+read(This0, bool) ->
+    {This1, Result} = read(This0, byte),
+    case Result of
+        {ok, Byte} -> {This1, {ok, Byte /= 0}};
+        Else -> {This1, Else}
     end;
 
-read(This, byte) ->
-    case read_data(This, 1) of
-        {ok, <<Val:8/integer-signed-big, _/binary>>} -> {ok, Val};
-        Else -> Else
+read(This0, byte) ->
+    {This1, Bytes} = read_data(This0, 1),
+    case Bytes of
+        {ok, <<Val:8/integer-signed-big, _/binary>>} -> {This1, {ok, Val}};
+        Else -> {This1, Else}
     end;
 
-read(This, i16) ->
-    case read_data(This, 2) of
-        {ok, <<Val:16/integer-signed-big, _/binary>>} -> {ok, Val};
-        Else -> Else
+read(This0, i16) ->
+    {This1, Bytes} = read_data(This0, 2),
+    case Bytes of
+        {ok, <<Val:16/integer-signed-big, _/binary>>} -> {This1, {ok, Val}};
+        Else -> {This1, Else}
     end;
 
-read(This, i32) ->
-    case read_data(This, 4) of
-        {ok, <<Val:32/integer-signed-big, _/binary>>} -> {ok, Val};
-        Else -> Else
+read(This0, i32) ->
+    {This1, Bytes} = read_data(This0, 4),
+    case Bytes of
+        {ok, <<Val:32/integer-signed-big, _/binary>>} -> {This1, {ok, Val}};
+        Else -> {This1, Else}
     end;
 
 %% unsigned ints aren't used by thrift itself, but it's used for the parsing
 %% of the packet version header. Without this special function BEAM works fine
 %% but hipe thinks it received a bad version header.
-read(This, ui32) ->
-    case read_data(This, 4) of
-        {ok, <<Val:32/integer-unsigned-big, _/binary>>} -> {ok, Val};
-        Else -> Else
+read(This0, ui32) ->
+    {This1, Bytes} = read_data(This0, 4),
+    case Bytes of
+        {ok, <<Val:32/integer-unsigned-big, _/binary>>} -> {This1, {ok, Val}};
+        Else -> {This1, Else}
     end;
 
-read(This, i64) ->
-    case read_data(This, 8) of
-        {ok, <<Val:64/integer-signed-big, _/binary>>} -> {ok, Val};
-        Else -> Else
+read(This0, i64) ->
+    {This1, Bytes} = read_data(This0, 8),
+    case Bytes of
+        {ok, <<Val:64/integer-signed-big, _/binary>>} -> {This1, {ok, Val}};
+        Else -> {This1, Else}
     end;
 
-read(This, double) ->
-    case read_data(This, 8) of
-        {ok, <<Val:64/float-signed-big, _/binary>>} -> {ok, Val};
-        Else -> Else
+read(This0, double) ->
+    {This1, Bytes} = read_data(This0, 8),
+    case Bytes of
+        {ok, <<Val:64/float-signed-big, _/binary>>} -> {This1, {ok, Val}};
+        Else -> {This1, Else}
     end;
 
 % returns a binary directly, call binary_to_list if necessary
-read(This, string) ->
-    {ok, Sz}  = read(This, i32),
-    {ok, Bin} = read_data(This, Sz).
+read(This0, string) ->
+    {This1, {ok, Sz}}  = read(This0, i32),
+    read_data(This1, Sz).
 
--spec read_data(#binary_protocol{}, non_neg_integer()) -> {ok, binary()} | {error, _Reason}.
-read_data(This, 0) -> {ok, <<>>};
-read_data(This, Len) when is_integer(Len), Len >= 0 ->
-    thrift_transport:read(This#binary_protocol.transport, Len).
+-spec read_data(#binary_protocol{}, non_neg_integer()) ->
+    {#binary_protocol{}, {ok, binary()} | {error, _Reason}}.
+read_data(This, 0) -> {This, {ok, <<>>}};
+read_data(This = #binary_protocol{transport = Trans}, Len) when is_integer(Len) andalso Len > 0 ->
+    Result = thrift_transport:read(Trans, Len),
+    {This, Result}.
 
 
 %%%% FACTORY GENERATION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%