diff --git a/lib/delphi/src/Thrift.Transport.pas b/lib/delphi/src/Thrift.Transport.pas
index 0e6f825..a460819 100644
--- a/lib/delphi/src/Thrift.Transport.pas
+++ b/lib/delphi/src/Thrift.Transport.pas
@@ -959,7 +959,7 @@
 begin
   if FOutputStream = nil then
   begin
-    raise TTransportException.Create( TTransportException.TExceptionType.NotOpen, 'Cannot read from null outputstream' );
+    raise TTransportException.Create( TTransportException.TExceptionType.NotOpen, 'Cannot write to null outputstream' );
   end;
 
   FOutputStream.Write( buf, off, len );