diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index ff631e61b2ea..f71c24844e8b 100644
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -3559,12 +3559,12 @@ arc_init(void)
 
 	/* set min cache to 1/32 of all memory, or 64MB, whichever is more */
 	arc_c_min = MAX(arc_c / 4, 64<<20);
-	/* set max to 3/4 of all memory, or all but 1GB, whichever is more */
-	if (arc_c * 8 >= 1<<30)
-		arc_c_max = (arc_c * 8) - (1<<30);
+	/* set max to 1/2 of all memory, or all but 4GB, whichever is more */
+	if (arc_c * 8 >= ((uint64_t)4<<30))
+		arc_c_max = (arc_c * 8) - ((uint64_t)4<<30);
 	else
 		arc_c_max = arc_c_min;
-	arc_c_max = MAX(arc_c * 6, arc_c_max);
+	arc_c_max = MAX(arc_c * 4, arc_c_max);
 
 	/*
 	 * Allow the tunables to override our calculations if they are