diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index dfea15b74394..4db6c06148b1 100644
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -8031,9 +8031,8 @@ l2arc_write_size(l2arc_dev_t *dev)
 	 */
 	size = l2arc_write_max;
 	if (size == 0) {
-		cmn_err(CE_NOTE, "Bad value for l2arc_write_max, value must "
-		    "be greater than zero, resetting it to the default (%d)",
-		    L2ARC_WRITE_SIZE);
+		cmn_err(CE_NOTE, "l2arc_write_max must be greater than zero, "
+		    "resetting it to the default (%d)", L2ARC_WRITE_SIZE);
 		size = l2arc_write_max = L2ARC_WRITE_SIZE;
 	}
 
@@ -8056,30 +8055,9 @@ l2arc_write_size(l2arc_dev_t *dev)
 	 * device. This is important in l2arc_evict(), otherwise infinite
 	 * iteration can occur.
 	 */
-	if (size > dev->l2ad_end - dev->l2ad_start) {
-		cmn_err(CE_NOTE, "l2arc_write_max or l2arc_write_boost "
-		    "plus the overhead of log blocks (persistent L2ARC, "
-		    "%llu bytes) exceeds the size of the cache device "
-		    "(guid %llu), resetting them to the default (%d)",
-		    (u_longlong_t)l2arc_log_blk_overhead(size, dev),
-		    (u_longlong_t)dev->l2ad_vdev->vdev_guid, L2ARC_WRITE_SIZE);
+	size = MIN(size, (dev->l2ad_end - dev->l2ad_start) / 4);
 
-		size = l2arc_write_max = l2arc_write_boost = L2ARC_WRITE_SIZE;
-
-		if (l2arc_trim_ahead > 1) {
-			cmn_err(CE_NOTE, "l2arc_trim_ahead set to 1");
-			l2arc_trim_ahead = 1;
-		}
-
-		if (arc_warm == B_FALSE)
-			size += l2arc_write_boost;
-
-		size += l2arc_log_blk_overhead(size, dev);
-		if (dev->l2ad_vdev->vdev_has_trim && l2arc_trim_ahead > 0) {
-			size += MAX(64 * 1024 * 1024,
-			    (size * l2arc_trim_ahead) / 100);
-		}
-	}
+	size = P2ROUNDUP(size, 1ULL << dev->l2ad_vdev->vdev_ashift);
 
 	return (size);
 
diff --git a/tests/zfs-tests/tests/functional/cache/cache_012_pos.ksh b/tests/zfs-tests/tests/functional/cache/cache_012_pos.ksh
index 74caa12a9cc4..945db71bf113 100755
--- a/tests/zfs-tests/tests/functional/cache/cache_012_pos.ksh
+++ b/tests/zfs-tests/tests/functional/cache/cache_012_pos.ksh
@@ -31,15 +31,13 @@
 #	2. Set l2arc_write_max to a value larger than the cache device.
 #	3. Create a file larger than the cache device and random read
 #		for 10 sec.
-#	4. Verify that l2arc_write_max is set back to the default.
-#	5. Set l2arc_write_max to a value less than the cache device size but
+#	4. Set l2arc_write_max to a value less than the cache device size but
 #		larger than the default (256MB).
-#	6. Record the l2_size.
-#	7. Random read for 1 sec.
-#	8. Record the l2_size again.
-#	9. If (6) <= (8) then we have not looped around yet.
-#	10. If (6) > (8) then we looped around. Break out of the loop and test.
-#	11. Destroy pool.
+#	5. Record the l2_size.
+#	6. Random read for 1 sec.
+#	7. Record the l2_size again.
+#	8. If (5) <= (7) then we have not looped around yet.
+#	9. Destroy pool.
 #
 
 verify_runnable "global"
@@ -93,10 +91,6 @@ log_must zfs set relatime=off $TESTPOOL
 log_must fio $FIO_SCRIPTS/mkfiles.fio
 log_must fio $FIO_SCRIPTS/random_reads.fio
 
-typeset write_max2=$(get_tunable L2ARC_WRITE_MAX)
-
-log_must test $write_max2 -eq $write_max
-
 log_must set_tunable32 L2ARC_WRITE_MAX $(( 256 * 1024 * 1024 ))
 export RUNTIME=1
 
@@ -108,8 +102,6 @@ while $do_once || [[ $l2_size1 -le $l2_size2 ]]; do
 	do_once=false
 done
 
-log_must test $l2_size1 -gt $l2_size2
-
 log_must zpool destroy $TESTPOOL
 
 log_pass "Looping around a cache device succeeds."