diff --git a/backend/hp.h b/backend/hp.h
index 9e7a7022c..b86ee04a8 100644
--- a/backend/hp.h
+++ b/backend/hp.h
@@ -104,7 +104,7 @@
   *
   */
 
-typedef int 		hp_bool_t;
+typedef unsigned int	hp_bool_t;
 typedef unsigned char	hp_byte_t;
 
 typedef enum { HP_CONNECT_SCSI, HP_CONNECT_DEVICE,