diff --git a/src/xpdev/filewrap.h b/src/xpdev/filewrap.h
index aab4a7ac02024f3b40f30f3a0d00c4e43b052332..c187e65904c57d20cd42e503e58dc63c5320cbf4 100644
--- a/src/xpdev/filewrap.h
+++ b/src/xpdev/filewrap.h
@@ -99,7 +99,7 @@
 		#define O_BINARY	0		/* all files in binary mode on Unix */
 		#endif
 		#undef	O_DENYNONE
-		#define O_DENYNONE  (1<<31)	/* req'd for Baja/nopen compatibility */
+		#define O_DENYNONE  (1U<<31)	/* req'd for Baja/nopen compatibility */
 
 		#define SH_DENYNO	2          /* no locks */
 		#ifdef F_SANEWRLCKNO