diff --git a/helper/geojsonify.js b/helper/geojsonify.js
index 9822ad02..94b41b84 100644
--- a/helper/geojsonify.js
+++ b/helper/geojsonify.js
@@ -46,7 +46,7 @@ function lookupLayer(src) {
     if (src.address) { return 'address'; }
   }
 
-  if (_.contains(type_mapping.types_list, src._type)) {
+  if (_.contains(type_mapping.types, src._type)) {
     return type_mapping.type_to_layer[src._type];
   }
 
diff --git a/helper/type_mapping.js b/helper/type_mapping.js
index a00979b7..ab7bbe56 100644
--- a/helper/type_mapping.js
+++ b/helper/type_mapping.js
@@ -1,19 +1,5 @@
 var extend = require('extend');
 
-var ALL_TYPES = [
-  'geoname',
-  'osmnode',
-  'osmway',
-  'admin0',
-  'admin1',
-  'admin2',
-  'neighborhood',
-  'locality',
-  'local_admin',
-  'osmaddress',
-  'openaddresses'
-];
-
 var TYPE_TO_SOURCE = {
   'geoname': 'gn',
   'osmnode': 'osm',
@@ -76,6 +62,13 @@ var LAYER_ALIASES = {
 
 var LAYER_WITH_ALIASES_TO_TYPE = extend({}, LAYER_ALIASES, LAYER_TO_TYPE);
 
+/*
+ * derive the list of types, sources, and layers from above mappings
+ */
+var TYPES   = Object.keys(TYPE_TO_SOURCE);
+var SOURCES = Object.keys(SOURCE_TO_TYPE);
+var LAYERS  = Object.keys(LAYER_TO_TYPE);
+
 /**
  * Calculate the set-style intersection of two arrays
  */
@@ -90,7 +83,9 @@ var sourceAndLayerToType = function sourceAndLayerToType(source, layer) {
 };
 
 module.exports = {
-  types_list: ALL_TYPES,
+  types: TYPES,
+  sources: SOURCES,
+  layers: LAYERS,
   type_to_source: TYPE_TO_SOURCE,
   type_to_layer: TYPE_TO_LAYER,
   source_to_type: SOURCE_TO_TYPE,
diff --git a/helper/types.js b/helper/types.js
index c057345f..aa3337e8 100644
--- a/helper/types.js
+++ b/helper/types.js
@@ -24,7 +24,7 @@ module.exports = function calculate_types(clean_types) {
    * perform a set intersection of their specified types
    */
   if (clean_types.from_layers || clean_types.from_sources) {
-    var types = type_mapping.types_list;
+    var types = type_mapping.types;
 
     if (clean_types.from_layers) {
       types = intersection(types, clean_types.from_layers);
diff --git a/test/unit/helper/type_mapping.js b/test/unit/helper/type_mapping.js
index fa50c191..144fadfb 100644
--- a/test/unit/helper/type_mapping.js
+++ b/test/unit/helper/type_mapping.js
@@ -4,9 +4,9 @@ var type_mapping = require('../../../helper/type_mapping');
 module.exports.tests = {};
 
 module.exports.tests.interfaces = function(test, common) {
-  test('types_list', function(t) {
-    t.ok(check.array(type_mapping.types_list), 'is array');
-    t.ok(check.hasLength(type_mapping.types_list, 11), 'has correct number of elements');
+  test('types list', function(t) {
+    t.ok(check.array(type_mapping.types), 'is array');
+    t.ok(check.hasLength(type_mapping.types, 11), 'has correct number of elements');
     t.end();
   });