diff --git a/src/common/port/parallel.h b/src/common/port/parallel.h
index d25529d..0a135af 100644
--- a/src/common/port/parallel.h
+++ b/src/common/port/parallel.h
@@ -52,7 +52,7 @@ private:
   int     _fd;
   TQString _device;
   struct RequestData {
-    int read, write;
+    unsigned int read, write;
   };
   static const RequestData REQUEST_DATA[Nb_RequestTypes];
   uchar _images[Nb_RequestTypes];