diff --git a/src/OT/Layout/GPOS/MarkMarkPosFormat1.hh b/src/OT/Layout/GPOS/MarkMarkPosFormat1.hh
index c48a74f77..3462fb846 100644
--- a/src/OT/Layout/GPOS/MarkMarkPosFormat1.hh
+++ b/src/OT/Layout/GPOS/MarkMarkPosFormat1.hh
@@ -100,7 +100,7 @@ struct MarkMarkPosFormat1
     /* now we search backwards for a suitable mark glyph until a non-mark glyph */
     hb_ot_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_input;
     skippy_iter.reset (buffer->idx, 1);
-    skippy_iter.set_lookup_props (c->lookup_props & ~LookupFlag::IgnoreFlags);
+    skippy_iter.set_lookup_props (c->lookup_props & ~(uint32_t)LookupFlag::IgnoreFlags);
     unsigned unsafe_from;
     if (!skippy_iter.prev (&unsafe_from))
     {