Index: uspace/drv/bus/isa/i8237.c
===================================================================
--- uspace/drv/bus/isa/i8237.c	(revision bb2a5b2f7e2770c16621489c3e3bd02d8522d38f)
+++ uspace/drv/bus/isa/i8237.c	(revision c762ad5ddae5ea40a56aa04d066fc4ac1787344c)
@@ -358,5 +358,5 @@
 
 	/* Buffers cannot cross 64K page boundaries */
-	if ((pa & 0xffff0000) !=  ((pa + size) & 0xffff0000))
+	if ((pa & 0xffff0000) != ((pa + size - 1) & 0xffff0000))
 		return EINVAL;