diff --git a/src/OT/Layout/Common/CoverageFormat1.hh b/src/OT/Layout/Common/CoverageFormat1.hh
index dd418b0bc..cdba7a505 100644
--- a/src/OT/Layout/Common/CoverageFormat1.hh
+++ b/src/OT/Layout/Common/CoverageFormat1.hh
@@ -103,7 +103,7 @@ struct CoverageFormat1_3
         intersect_glyphs << glyphArray[i];
   }
 
-  unsigned cost () const { return 1; }
+  unsigned cost () const { return hb_bit_storage ((unsigned) glyphArray.len); /* bsearch cost */ }
 
   template <typename set_t>
   bool collect_coverage (set_t *glyphs) const
diff --git a/src/hb-ot-layout-gsubgpos.hh b/src/hb-ot-layout-gsubgpos.hh
index 03d849165..6c62d5660 100644
--- a/src/hb-ot-layout-gsubgpos.hh
+++ b/src/hb-ot-layout-gsubgpos.hh
@@ -3882,8 +3882,7 @@ struct ChainContextFormat2_5
 
   unsigned cache_cost () const
   {
-    unsigned c = (this+lookaheadClassDef).cost () * ruleSet.len;
-    return c >= 4 ? c : 0;
+    return (this+lookaheadClassDef).cost () * ruleSet.len;
   }
   static void * cache_func (void *p, hb_ot_lookup_cache_op_t op)
   {
@@ -4438,6 +4437,9 @@ struct hb_ot_layout_lookup_accelerator_t
       thiz->digest.union_ (subtable.digest);
 
 #ifndef HB_NO_OT_LAYOUT_LOOKUP_CACHE
+    if (c_accelerate_subtables.cache_user_cost <= 1)
+      c_accelerate_subtables.cache_user_idx = (unsigned) -1;
+
     thiz->cache_user_idx = c_accelerate_subtables.cache_user_idx;
 
     if (thiz->cache_user_idx != (unsigned) -1)