diff --git a/src/hb-aat-layout-feat-table.hh b/src/hb-aat-layout-feat-table.hh
index ec617080d..359e859cf 100644
--- a/src/hb-aat-layout-feat-table.hh
+++ b/src/hb-aat-layout-feat-table.hh
@@ -129,6 +129,8 @@ struct FeatureName
 
   hb_ot_name_id_t get_feature_name_id () const { return nameIndex; }
 
+  bool is_exclusive () const { return featureFlags & Exclusive; }
+
   /* A FeatureName with no settings is meaningless */
   bool has_data () const { return nSettings; }
 
diff --git a/src/hb-aat-layout-morx-table.hh b/src/hb-aat-layout-morx-table.hh
index d8df579f5..c6b5aa53f 100644
--- a/src/hb-aat-layout-morx-table.hh
+++ b/src/hb-aat-layout-morx-table.hh
@@ -948,8 +948,10 @@ struct Chain
 	hb_aat_layout_feature_type_t type = (hb_aat_layout_feature_type_t) (unsigned int) feature.featureType;
 	hb_aat_layout_feature_selector_t setting = (hb_aat_layout_feature_selector_t) (unsigned int) feature.featureSetting;
       retry:
-	const hb_aat_map_builder_t::feature_info_t *info = map->features.bsearch (type);
-	if (info && info->setting == setting)
+        // Check whether this type/setting pair was requested in the map, and if so, apply its flags.
+        // (The search here only looks at the type and setting fields of feature_info_t.)
+        hb_aat_map_builder_t::feature_info_t info = { type, setting, false, 0 };
+	if (map->features.bsearch (info))
 	{
 	  flags &= feature.disableFlags;
 	  flags |= feature.enableFlags;
diff --git a/src/hb-aat-map.cc b/src/hb-aat-map.cc
index 65df85d36..255684231 100644
--- a/src/hb-aat-map.cc
+++ b/src/hb-aat-map.cc
@@ -48,12 +48,15 @@ void hb_aat_map_builder_t::add_feature (hb_tag_t tag, unsigned value)
     info->type = HB_AAT_LAYOUT_FEATURE_TYPE_CHARACTER_ALTERNATIVES;
     info->setting = (hb_aat_layout_feature_selector_t) value;
     info->seq = features.length;
+    info->is_exclusive = true;
     return;
   }
 
   const hb_aat_feature_mapping_t *mapping = hb_aat_layout_find_feature_mapping (tag);
   if (!mapping) return;
-  if (!face->table.feat->exposes_feature (mapping->aatFeatureType))
+
+  const AAT::FeatureName* feature = &face->table.feat->get_feature (mapping->aatFeatureType);
+  if (!feature->has_data ())
   {
     /* Special case: Chain::compile_flags will fall back to the deprecated version of
      * small-caps if necessary, so we need to check for that possibility.
@@ -61,7 +64,8 @@ void hb_aat_map_builder_t::add_feature (hb_tag_t tag, unsigned value)
     if (mapping->aatFeatureType == HB_AAT_LAYOUT_FEATURE_TYPE_LOWER_CASE &&
         mapping->selectorToEnable == HB_AAT_LAYOUT_FEATURE_SELECTOR_LOWER_CASE_SMALL_CAPS)
     {
-      if (!face->table.feat->exposes_feature (HB_AAT_LAYOUT_FEATURE_TYPE_LETTER_CASE)) return;
+      feature = &face->table.feat->get_feature (HB_AAT_LAYOUT_FEATURE_TYPE_LETTER_CASE);
+      if (!feature->has_data ()) return;
     }
     else return;
   }
@@ -70,6 +74,7 @@ void hb_aat_map_builder_t::add_feature (hb_tag_t tag, unsigned value)
   info->type = mapping->aatFeatureType;
   info->setting = value ? mapping->selectorToEnable : mapping->selectorToDisable;
   info->seq = features.length;
+  info->is_exclusive = feature->is_exclusive ();
 }
 
 void
@@ -81,7 +86,11 @@ hb_aat_map_builder_t::compile (hb_aat_map_t  &m)
     features.qsort ();
     unsigned int j = 0;
     for (unsigned int i = 1; i < features.length; i++)
-      if (features[i].type != features[j].type)
+      if (features[i].type != features[j].type ||
+          /* Nonexclusive feature selectors come in even/odd pairs to turn a setting on/off
+           * respectively, so we mask out the low-order bit when checking for "duplicates"
+           * (selectors referring to the same feature setting) here. */
+          (!features[i].is_exclusive && ((features[i].setting & ~1) != (features[j].setting & ~1))))
 	features[++j] = features[i];
     features.shrink (j + 1);
   }
diff --git a/src/hb-aat-map.hh b/src/hb-aat-map.hh
index 0065207cc..1cf5a8a13 100644
--- a/src/hb-aat-map.hh
+++ b/src/hb-aat-map.hh
@@ -64,19 +64,24 @@ struct hb_aat_map_builder_t
   {
     hb_aat_layout_feature_type_t  type;
     hb_aat_layout_feature_selector_t  setting;
+    bool is_exclusive;
     unsigned  seq; /* For stable sorting only. */
 
     HB_INTERNAL static int cmp (const void *pa, const void *pb)
     {
       const feature_info_t *a = (const feature_info_t *) pa;
       const feature_info_t *b = (const feature_info_t *) pb;
-      return (a->type != b->type) ? (a->type < b->type ? -1 : 1) :
-	     (a->seq < b->seq ? -1 : a->seq > b->seq ? 1 : 0);
+      if (a->type != b->type) return (a->type < b->type ? -1 : 1);
+      if (!a->is_exclusive &&
+          (a->setting & ~1) != (b->setting & ~1)) return (a->setting < b->setting ? -1 : 1);
+	    return (a->seq < b->seq ? -1 : a->seq > b->seq ? 1 : 0);
     }
 
-    int cmp (hb_aat_layout_feature_type_t ty) const
+    /* compares type & setting only, not is_exclusive flag or seq number */
+    int cmp (const feature_info_t& f) const
     {
-      return (ty != type) ? (ty < type ? -1 : 1) : 0;
+      return (f.type != type) ? (f.type < type ? -1 : 1) :
+             (f.setting != setting) ? (f.setting < setting ? -1 : 1) : 0;
     }
   };