diff --git a/module/zfs/dnode_sync.c b/module/zfs/dnode_sync.c
index 2ed8058e8..8e39af83b 100644
--- a/module/zfs/dnode_sync.c
+++ b/module/zfs/dnode_sync.c
@@ -175,19 +175,21 @@ free_blocks(dnode_t *dn, blkptr_t *bp, int num, dmu_tx_t *tx)
 static void
 free_verify(dmu_buf_impl_t *db, uint64_t start, uint64_t end, dmu_tx_t *tx)
 {
-	int off, num;
-	int i, err, epbs;
+	uint64_t off, num, i, j;
+	unsigned int epbs;
+	int err;
 	uint64_t txg = tx->tx_txg;
 	dnode_t *dn;
 
 	DB_DNODE_ENTER(db);
 	dn = DB_DNODE(db);
 	epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
-	off = start - (db->db_blkid * 1<<epbs);
+	off = start - (db->db_blkid << epbs);
 	num = end - start + 1;
 
-	ASSERT3U(off, >=, 0);
-	ASSERT3U(num, >=, 0);
+	ASSERT3U(dn->dn_phys->dn_indblkshift, >=, SPA_BLKPTRSHIFT);
+	ASSERT3U(end + 1, >=, start);
+	ASSERT3U(start, >=, (db->db_blkid << epbs));
 	ASSERT3U(db->db_level, >, 0);
 	ASSERT3U(db->db.db_size, ==, 1 << dn->dn_phys->dn_indblkshift);
 	ASSERT3U(off+num, <=, db->db.db_size >> SPA_BLKPTRSHIFT);
@@ -197,7 +199,6 @@ free_verify(dmu_buf_impl_t *db, uint64_t start, uint64_t end, dmu_tx_t *tx)
 		uint64_t *buf;
 		dmu_buf_impl_t *child;
 		dbuf_dirty_record_t *dr;
-		int j;
 
 		ASSERT(db->db_level == 1);
 
@@ -217,8 +218,11 @@ free_verify(dmu_buf_impl_t *db, uint64_t start, uint64_t end, dmu_tx_t *tx)
 			for (j = 0; j < child->db.db_size >> 3; j++) {
 				if (buf[j] != 0) {
 					panic("freed data not zero: "
-					    "child=%p i=%d off=%d num=%d\n",
-					    (void *)child, i, off, num);
+					    "child=%p i=%llu off=%llu "
+					    "num=%llu\n",
+					    (void *)child, (u_longlong_t)i,
+					    (u_longlong_t)off,
+					    (u_longlong_t)num);
 				}
 			}
 		}
@@ -234,8 +238,11 @@ free_verify(dmu_buf_impl_t *db, uint64_t start, uint64_t end, dmu_tx_t *tx)
 			for (j = 0; j < child->db.db_size >> 3; j++) {
 				if (buf[j] != 0) {
 					panic("freed data not zero: "
-					    "child=%p i=%d off=%d num=%d\n",
-					    (void *)child, i, off, num);
+					    "child=%p i=%llu off=%llu "
+					    "num=%llu\n",
+					    (void *)child, (u_longlong_t)i,
+					    (u_longlong_t)off,
+					    (u_longlong_t)num);
 				}
 			}
 		}