diff --git a/Lib/fontTools/ttLib/tables/S__i_l_l.py b/Lib/fontTools/ttLib/tables/S__i_l_l.py
index 4fdf05390..cbee3207e 100644
--- a/Lib/fontTools/ttLib/tables/S__i_l_l.py
+++ b/Lib/fontTools/ttLib/tables/S__i_l_l.py
@@ -43,12 +43,13 @@ class table_S__i_l_l(DefaultTable.DefaultTable):
     def compile(self, ttFont):
         ldat = b""
         fdat = b""
-        offset = 0
+        offset = len(self.langs)
         for c, inf in sorted(self.langs.items()):
-            ldat += struct.pack(">4sHH", c.encode('utf8'), len(inf), 8 * (offset + len(self.langs) + 1))
+            ldat += struct.pack(">4sHH", c.encode('utf8'), len(inf), 8 * offset + 20)
             for fid, val in inf:
                 fdat += struct.pack(">LHH", fid, val, 0)
             offset += len(inf)
+        ldat += struct.pack(">LHH", 0x80808080, 0, 8 * offset + 20)
         return sstruct.pack(Sill_hdr, self) + grUtils.bininfo(len(self.langs)) + \
                 ldat + fdat