diff --git a/src/hb-subset-input.cc b/src/hb-subset-input.cc
index ad2d6b3fc..b70c86a5b 100644
--- a/src/hb-subset-input.cc
+++ b/src/hb-subset-input.cc
@@ -45,23 +45,16 @@ hb_subset_input_create_or_fail (void)
   if (unlikely (!input))
     return nullptr;
 
-  input->unicodes = hb_set_create ();
-  input->glyphs = hb_set_create ();
-  input->name_ids = hb_set_create ();
-  hb_set_add_range (input->name_ids, 0, 6);
-  input->name_languages = hb_set_create ();
-  hb_set_add (input->name_languages, 0x0409);
-  input->layout_features = hb_set_create ();
-  input->drop_tables = hb_set_create ();
-  input->no_subset_tables = hb_set_create ();
+  input->sets.init ();
+  input->sets.set (HB_SUBSET_SETS_GLYPH_INDEX, hb_set_create ());
+  input->sets.set (HB_SUBSET_SETS_UNICODE, hb_set_create ());
+  input->sets.set (HB_SUBSET_SETS_NO_SUBSET_TABLE_TAG, hb_set_create ());
+  input->sets.set (HB_SUBSET_SETS_DROP_TABLE_TAG, hb_set_create ());
+  input->sets.set (HB_SUBSET_SETS_NAME_ID, hb_set_create ());
+  input->sets.set (HB_SUBSET_SETS_NAME_LANG_ID, hb_set_create ());
+  input->sets.set (HB_SUBSET_SETS_LAYOUT_FEATURE_TAG, hb_set_create ());
 
-  if (unlikely (input->unicodes->in_error ()
-                || input->glyphs->in_error ()
-                || input->name_ids->in_error ()
-                || input->name_languages->in_error ()
-                || input->layout_features->in_error ()
-                || input->drop_tables->in_error ()
-                || input->no_subset_tables->in_error ()))
+  if (input->in_error ())
   {
     hb_subset_input_destroy (input);
     return nullptr;
@@ -69,6 +62,9 @@ hb_subset_input_create_or_fail (void)
 
   input->flags = HB_SUBSET_FLAGS_DEFAULT;
 
+  hb_set_add_range (input->name_ids (), 0, 6);
+  hb_set_add (input->name_languages (), 0x0409);
+
   hb_tag_t default_drop_tables[] = {
     // Layout disabled by default
     HB_TAG ('m', 'o', 'r', 'x'),
@@ -93,7 +89,7 @@ hb_subset_input_create_or_fail (void)
     HB_TAG ('S', 'i', 'l', 'f'),
     HB_TAG ('S', 'i', 'l', 'l'),
   };
-  input->drop_tables->add_array (default_drop_tables, ARRAY_LENGTH (default_drop_tables));
+  input->drop_tables ()->add_array (default_drop_tables, ARRAY_LENGTH (default_drop_tables));
 
   hb_tag_t default_no_subset_tables[] = {
     HB_TAG ('a', 'v', 'a', 'r'),
@@ -108,8 +104,8 @@ hb_subset_input_create_or_fail (void)
     HB_TAG ('c', 'v', 'a', 'r'),
     HB_TAG ('S', 'T', 'A', 'T'),
   };
-  input->no_subset_tables->add_array (default_no_subset_tables,
-				      ARRAY_LENGTH (default_no_subset_tables));
+  input->no_subset_tables ()->add_array (default_no_subset_tables,
+                                         ARRAY_LENGTH (default_no_subset_tables));
 
   //copied from _layout_features_groups in fonttools
   hb_tag_t default_layout_features[] = {
@@ -198,7 +194,13 @@ hb_subset_input_create_or_fail (void)
     HB_TAG ('b', 'l', 'w', 'm'),
   };
 
-  input->layout_features->add_array (default_layout_features, ARRAY_LENGTH (default_layout_features));
+  input->layout_features ()->add_array (default_layout_features, ARRAY_LENGTH (default_layout_features));
+
+  if (input->in_error ())
+  {
+    hb_subset_input_destroy (input);
+    return nullptr;
+  }
   return input;
 }
 
@@ -232,13 +234,10 @@ hb_subset_input_destroy (hb_subset_input_t *input)
 {
   if (!hb_object_destroy (input)) return;
 
-  hb_set_destroy (input->unicodes);
-  hb_set_destroy (input->glyphs);
-  hb_set_destroy (input->name_ids);
-  hb_set_destroy (input->name_languages);
-  hb_set_destroy (input->drop_tables);
-  hb_set_destroy (input->layout_features);
-  hb_set_destroy (input->no_subset_tables);
+  for (hb_set_t* set : input->sets.values ())
+    hb_set_destroy (set);
+
+  input->sets.fini ();
 
   hb_free (input);
 }
@@ -258,7 +257,7 @@ hb_subset_input_destroy (hb_subset_input_t *input)
 HB_EXTERN hb_set_t *
 hb_subset_input_unicode_set (hb_subset_input_t *input)
 {
-  return input->unicodes;
+  return input->unicodes ();
 }
 
 /**
@@ -275,7 +274,7 @@ hb_subset_input_unicode_set (hb_subset_input_t *input)
 HB_EXTERN hb_set_t *
 hb_subset_input_glyph_set (hb_subset_input_t *input)
 {
-  return input->glyphs;
+  return input->glyphs ();
 }
 
 /**
@@ -292,7 +291,7 @@ hb_subset_input_glyph_set (hb_subset_input_t *input)
 HB_EXTERN hb_set_t *
 hb_subset_input_nameid_set (hb_subset_input_t *input)
 {
-  return input->name_ids;
+  return input->name_ids ();
 }
 
 /**
@@ -309,7 +308,7 @@ hb_subset_input_nameid_set (hb_subset_input_t *input)
 HB_EXTERN hb_set_t *
 hb_subset_input_namelangid_set (hb_subset_input_t *input)
 {
-  return input->name_languages;
+  return input->name_languages ();
 }
 
 
@@ -327,7 +326,7 @@ hb_subset_input_namelangid_set (hb_subset_input_t *input)
 HB_EXTERN hb_set_t *
 hb_subset_input_layout_features_set (hb_subset_input_t *input)
 {
-  return input->layout_features;
+  return input->layout_features ();
 }
 
 /**
@@ -344,7 +343,25 @@ hb_subset_input_layout_features_set (hb_subset_input_t *input)
 HB_EXTERN hb_set_t *
 hb_subset_input_drop_tables_set (hb_subset_input_t *input)
 {
-  return input->drop_tables;
+  return input->drop_tables ();
+}
+
+/**
+ * hb_subset_input_set:
+ * @input: a #hb_subset_input_t object.
+ * @set_type: a #hb_subset_sets_t set type.
+ *
+ * Gets the set of the specified type.
+ *
+ * Return value: (transfer none): pointer to the #hb_set_t of the specified type.
+ *
+ * Since: REPLACEME
+ **/
+HB_EXTERN hb_set_t *
+hb_subset_input_set (hb_subset_input_t *input, hb_subset_sets_t set_type)
+{
+  // TODO(garretrieger): add test for this method.
+  return input->sets.get (set_type);
 }
 
 /**
@@ -361,7 +378,7 @@ hb_subset_input_drop_tables_set (hb_subset_input_t *input)
 HB_EXTERN hb_set_t *
 hb_subset_input_no_subset_tables_set (hb_subset_input_t *input)
 {
-  return input->no_subset_tables;
+  return input->no_subset_tables ();
 }
 
 
diff --git a/src/hb-subset-input.hh b/src/hb-subset-input.hh
index ddc35f287..82ffb6d73 100644
--- a/src/hb-subset-input.hh
+++ b/src/hb-subset-input.hh
@@ -31,6 +31,8 @@
 #include "hb.hh"
 
 #include "hb-subset.h"
+#include "hb-map.hh"
+#include "hb-set.hh"
 
 #include "hb-font.hh"
 
@@ -40,23 +42,90 @@ struct hb_subset_input_t
 {
   hb_object_header_t header;
 
-  hb_set_t *unicodes;         // invert safe
-  hb_set_t *glyphs;           // invert safe
-  hb_set_t *name_ids;         // invert safe
-  hb_set_t *name_languages;   // invert safe
-  hb_set_t *no_subset_tables; // invert safe
-  hb_set_t *drop_tables;      // invert safe
-  hb_set_t *layout_features;  // invert safe
+  hb_hashmap_t<unsigned, hb_set_t*> sets;
 
   unsigned flags;
 
-  /* TODO
-   *
-   * features
-   * lookups
-   * name_ids
-   * ...
-   */
+  inline hb_set_t* unicodes()
+  {
+    return sets.get (HB_SUBSET_SETS_UNICODE);
+  }
+
+  inline const hb_set_t* unicodes() const
+  {
+    return sets.get (HB_SUBSET_SETS_UNICODE);
+  }
+
+  inline hb_set_t* glyphs ()
+  {
+    return sets.get (HB_SUBSET_SETS_GLYPH_INDEX);
+  }
+
+  inline const hb_set_t* glyphs () const
+  {
+    return sets.get (HB_SUBSET_SETS_GLYPH_INDEX);
+  }
+
+  inline hb_set_t* name_ids ()
+  {
+    return sets.get (HB_SUBSET_SETS_NAME_ID);
+  }
+
+  inline const hb_set_t* name_ids () const
+  {
+    return sets.get (HB_SUBSET_SETS_NAME_ID);
+  }
+
+  inline hb_set_t* name_languages ()
+  {
+    return sets.get (HB_SUBSET_SETS_NAME_LANG_ID);
+  }
+
+  inline const hb_set_t* name_languages () const
+  {
+    return sets.get (HB_SUBSET_SETS_NAME_LANG_ID);
+  }
+
+  inline hb_set_t* no_subset_tables ()
+  {
+    return sets.get (HB_SUBSET_SETS_NO_SUBSET_TABLE_TAG);
+  }
+
+  inline const hb_set_t* no_subset_tables () const
+  {
+    return sets.get (HB_SUBSET_SETS_NO_SUBSET_TABLE_TAG);
+  }
+
+  inline hb_set_t* drop_tables ()
+  {
+    return sets.get (HB_SUBSET_SETS_DROP_TABLE_TAG);
+  }
+
+  inline const hb_set_t* drop_tables () const
+  {
+    return sets.get (HB_SUBSET_SETS_DROP_TABLE_TAG);
+  }
+
+  inline hb_set_t* layout_features ()
+  {
+    return sets.get (HB_SUBSET_SETS_LAYOUT_FEATURE_TAG);
+  }
+
+  inline const hb_set_t* layout_features () const
+  {
+    return sets.get (HB_SUBSET_SETS_LAYOUT_FEATURE_TAG);
+  }
+
+  bool in_error () const
+  {
+    if (sets.in_error ()) return true;
+    for (const hb_set_t* set : sets.values ())
+    {
+      if (unlikely (set->in_error ()))
+        return true;
+    }
+    return false;
+  }
 };
 
 
diff --git a/src/hb-subset-plan.cc b/src/hb-subset-plan.cc
index fb23a6488..d6c7f8fa6 100644
--- a/src/hb-subset-plan.cc
+++ b/src/hb-subset-plan.cc
@@ -456,13 +456,13 @@ hb_subset_plan_create (hb_face_t	 *face,
   plan->successful = true;
   plan->flags = input->flags;
   plan->unicodes = hb_set_create ();
-  plan->name_ids = hb_set_copy (input->name_ids);
+  plan->name_ids = hb_set_copy (input->name_ids ());
   _nameid_closure (face, plan->name_ids);
-  plan->name_languages = hb_set_copy (input->name_languages);
-  plan->layout_features = hb_set_copy (input->layout_features);
-  plan->glyphs_requested = hb_set_copy (input->glyphs);
-  plan->drop_tables = hb_set_copy (input->drop_tables);
-  plan->no_subset_tables = hb_set_copy (input->no_subset_tables);
+  plan->name_languages = hb_set_copy (input->name_languages ());
+  plan->layout_features = hb_set_copy (input->layout_features ());
+  plan->glyphs_requested = hb_set_copy (input->glyphs ());
+  plan->drop_tables = hb_set_copy (input->drop_tables ());
+  plan->no_subset_tables = hb_set_copy (input->no_subset_tables ());
   plan->source = hb_face_reference (face);
   plan->dest = hb_face_builder_create ();
 
@@ -490,12 +490,12 @@ hb_subset_plan_create (hb_face_t	 *face,
     return plan;
   }
 
-  _populate_unicodes_to_retain (input->unicodes, input->glyphs, plan);
+  _populate_unicodes_to_retain (input->unicodes (), input->glyphs (), plan);
 
   _populate_gids_to_retain (plan,
-			    !input->drop_tables->has (HB_OT_TAG_GSUB),
-			    !input->drop_tables->has (HB_OT_TAG_GPOS),
-			    !input->drop_tables->has (HB_OT_TAG_GDEF));
+			    !input->drop_tables ()->has (HB_OT_TAG_GSUB),
+			    !input->drop_tables ()->has (HB_OT_TAG_GPOS),
+			    !input->drop_tables ()->has (HB_OT_TAG_GDEF));
 
   _create_old_gid_to_new_gid_map (face,
                                   input->flags & HB_SUBSET_FLAGS_RETAIN_GIDS,