diff --git a/src/hb-map.hh b/src/hb-map.hh
index f2a65a821..406730831 100644
--- a/src/hb-map.hh
+++ b/src/hb-map.hh
@@ -31,22 +31,28 @@
 
 
 /*
- * hb_map_t
+ * hb_hashmap_t
  */
 
-struct hb_map_t
+template <typename K, typename V,
+	  K kINVALID = hb_is_pointer (K) ? 0 : (K) -1,
+	  V vINVALID = hb_is_pointer (V) ? 0 : (V) -1>
+struct hb_hashmap_t
 {
-  HB_NO_COPY_ASSIGN (hb_map_t);
-  hb_map_t ()  { init (); }
-  ~hb_map_t () { fini (); }
+  HB_NO_COPY_ASSIGN (hb_hashmap_t);
+  hb_hashmap_t ()  { init (); }
+  ~hb_hashmap_t () { fini (); }
+
+  static_assert (hb_is_integer (K) || hb_is_pointer (K), "");
+  static_assert (hb_is_integer (V) || hb_is_pointer (V), "");
 
   struct item_t
   {
-    hb_codepoint_t key;
-    hb_codepoint_t value;
+    K key;
+    V value;
 
-    bool is_unused () const    { return key == INVALID; }
-    bool is_tombstone () const { return key != INVALID && value == INVALID; }
+    bool is_unused () const    { return key == kINVALID; }
+    bool is_tombstone () const { return key != kINVALID && value == vINVALID; }
   };
 
   hb_object_header_t header;
@@ -110,7 +116,7 @@ struct hb_map_t
     /* Insert back old items. */
     if (old_items)
       for (unsigned int i = 0; i < old_size; i++)
-	if (old_items[i].key != INVALID && old_items[i].value != INVALID)
+	if (old_items[i].key != kINVALID && old_items[i].value != vINVALID)
 	  set (old_items[i].key, old_items[i].value);
 
     free (old_items);
@@ -118,14 +124,14 @@ struct hb_map_t
     return true;
   }
 
-  void set (hb_codepoint_t key, hb_codepoint_t value)
+  void set (K key, V value)
   {
     if (unlikely (!successful)) return;
-    if (unlikely (key == INVALID)) return;
+    if (unlikely (key == kINVALID)) return;
     if ((occupancy + occupancy / 2) >= mask && !resize ()) return;
     unsigned int i = bucket_for (key);
 
-    if (value == INVALID && items[i].key != key)
+    if (value == vINVALID && items[i].key != key)
       return; /* Trying to delete non-existent key. */
 
     if (!items[i].is_unused ())
@@ -143,24 +149,22 @@ struct hb_map_t
       population++;
 
   }
-  hb_codepoint_t get (hb_codepoint_t key) const
+  V get (K key) const
   {
-    if (unlikely (!items)) return INVALID;
+    if (unlikely (!items)) return vINVALID;
     unsigned int i = bucket_for (key);
-    return items[i].key == key ? items[i].value : INVALID;
+    return items[i].key == key ? items[i].value : vINVALID;
   }
 
-  void del (hb_codepoint_t key) { set (key, INVALID); }
-
-  static constexpr hb_codepoint_t INVALID = HB_MAP_VALUE_INVALID;
+  void del (K key) { set (key, vINVALID); }
 
   /* Has interface. */
-  static constexpr hb_codepoint_t SENTINEL = INVALID;
-  typedef hb_codepoint_t value_t;
-  value_t operator [] (hb_codepoint_t k) const { return get (k); }
-  bool has (hb_codepoint_t k) const { return (*this)[k] != SENTINEL; }
+  static constexpr V SENTINEL = vINVALID;
+  typedef V value_t;
+  value_t operator [] (K k) const { return get (k); }
+  bool has (K k) const { return (*this)[k] != SENTINEL; }
   /* Projection. */
-  hb_codepoint_t operator () (hb_codepoint_t k) const { return get (k); }
+  V operator () (K k) const { return get (k); }
 
   void clear ()
   {
@@ -174,20 +178,20 @@ struct hb_map_t
 
   protected:
 
-  unsigned int bucket_for (hb_codepoint_t key) const
+  unsigned int bucket_for (K key) const
   {
     unsigned int i = hb_hash (key) % prime;
     unsigned int step = 0;
-    unsigned int tombstone = INVALID;
+    unsigned int tombstone = (unsigned) -1;
     while (!items[i].is_unused ())
     {
       if (items[i].key == key)
         return i;
-      if (tombstone == INVALID && items[i].is_tombstone ())
+      if (tombstone == (unsigned) -1 && items[i].is_tombstone ())
         tombstone = i;
       i = (i + ++step) & mask;
     }
-    return tombstone == INVALID ? i : tombstone;
+    return tombstone == (unsigned) -1 ? i : tombstone;
   }
 
   static unsigned int prime_for (unsigned int shift)
@@ -242,5 +246,10 @@ struct hb_map_t
   }
 };
 
+struct hb_map_t : hb_hashmap_t<hb_codepoint_t,
+			       hb_codepoint_t,
+			       HB_MAP_VALUE_INVALID,
+			       HB_MAP_VALUE_INVALID> {};
+
 
 #endif /* HB_MAP_HH */