diff --git a/src/hb-ot-layout-common-private.hh b/src/hb-ot-layout-common-private.hh
index 81e4dc911..9c3de50f9 100644
--- a/src/hb-ot-layout-common-private.hh
+++ b/src/hb-ot-layout-common-private.hh
@@ -295,7 +295,9 @@ struct Lookup
 
   inline bool sanitize (SANITIZE_ARG_DEF) {
     TRACE_SANITIZE ();
-    if (!(SANITIZE_SELF () && HB_LIKELY ((subTable).sanitize_shallow (SANITIZE_ARG)))) return false;
+    /* We sanitize subtables shallow here since we don't have their actual
+     * type.  Real sanitize of the referenced data is done by GSUB/GPOS/... */
+    if (!(SANITIZE_SELF () && HB_LIKELY (subTable.sanitize_shallow (SANITIZE_ARG)))) return false;
     if (HB_UNLIKELY (lookupFlag & LookupFlag::UseMarkFilteringSet))
     {
       USHORT &markFilteringSet = StructAfter<USHORT> (subTable);