diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
index 1697a6320..a283b0622 100644
--- a/module/zfs/dmu.c
+++ b/module/zfs/dmu.c
@@ -719,8 +719,8 @@ get_next_chunk(dnode_t *dn, uint64_t *start, uint64_t minimum, uint64_t *l1blks)
 	uint64_t blks;
 	uint64_t maxblks = DMU_MAX_ACCESS >> (dn->dn_indblkshift + 1);
 	/* bytes of data covered by a level-1 indirect block */
-	uint64_t iblkrange =
-	    dn->dn_datablksz * EPB(dn->dn_indblkshift, SPA_BLKPTRSHIFT);
+	uint64_t iblkrange = (uint64_t)dn->dn_datablksz *
+	    EPB(dn->dn_indblkshift, SPA_BLKPTRSHIFT);
 
 	ASSERT3U(minimum, <=, *start);