diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index 7c21e9b428cc..aba08977d9ee 100644
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -1705,6 +1705,7 @@ arc_buf_try_copy_decompressed_data(arc_buf_t *buf)
 {
 	arc_buf_hdr_t *hdr = buf->b_hdr;
 	boolean_t copied = B_FALSE;
+	int nbufs = 0;
 
 	ASSERT(HDR_HAS_L1HDR(hdr));
 	ASSERT3P(buf->b_data, !=, NULL);
@@ -1716,7 +1717,7 @@ arc_buf_try_copy_decompressed_data(arc_buf_t *buf)
 		if (from == buf) {
 			continue;
 		}
-
+		nbufs++;
 		if (!ARC_BUF_COMPRESSED(from)) {
 			bcopy(from->b_data, buf->b_data, arc_buf_size(buf));
 			copied = B_TRUE;
@@ -1728,9 +1729,18 @@ arc_buf_try_copy_decompressed_data(arc_buf_t *buf)
 	 * There were no decompressed bufs, so there should not be a
 	 * checksum on the hdr either.
 	 */
-	if (zfs_flags & ZFS_DEBUG_MODIFY)
-		EQUIV(!copied, hdr->b_l1hdr.b_freeze_cksum == NULL);
-
+	if (zfs_flags & ZFS_DEBUG_MODIFY) {
+		if (nbufs)
+			EQUIV(!copied, hdr->b_l1hdr.b_freeze_cksum == NULL);
+		else if (!ARC_BUF_COMPRESSED(buf) &&
+		    hdr->b_l1hdr.b_freeze_cksum != NULL) {
+			zio_cksum_t cksum;
+			fletcher_2_native(buf->b_data, arc_buf_size(buf), NULL,
+			    &cksum);
+			ASSERT0(memcmp(&cksum, hdr->b_l1hdr.b_freeze_cksum,
+			    sizeof (zio_cksum_t)));
+		}
+	}
 	return (copied);
 }
 
diff --git a/module/zfs/dbuf_stats.c b/module/zfs/dbuf_stats.c
index a2f3c580ee6c..12bb568a08cc 100644
--- a/module/zfs/dbuf_stats.c
+++ b/module/zfs/dbuf_stats.c
@@ -134,7 +134,8 @@ dbuf_stats_hash_table_data(char *buf, size_t size, void *data)
 
 	ASSERT3S(dsh->idx, >=, 0);
 	ASSERT3S(dsh->idx, <=, h->hash_table_mask);
-	memset(buf, 0, size);
+	if (size)
+		buf[0] = 0;
 
 	mutex_enter(DBUF_HASH_MUTEX(h, dsh->idx));
 	for (db = h->hash_table[dsh->idx]; db != NULL; db = db->db_hash_next) {