diff --git a/build.js b/build.js
index 5ca513330..84d5d5136 100644
--- a/build.js
+++ b/build.js
@@ -59,7 +59,7 @@ function generateCategories() {
 
         categories[id] = field;
     });
-    fs.writeFileSync('data/presets/categories.json', stringify(categories));
+    return categories;
 }
 
 function generateFields() {
@@ -86,7 +86,7 @@ function generateFields() {
 
         fields[id] = field;
     });
-    fs.writeFileSync('data/presets/fields.json', stringify(fields));
+    return fields;
 }
 
 function suggestionsToPresets(presets) {
@@ -171,20 +171,19 @@ function generatePresets() {
 
     presets = _.merge(presets, suggestionsToPresets(presets));
 
-    fs.writeFileSync('data/presets/presets.json', stringify(presets));
-    fs.writeFileSync('js/id/core/area_keys.js', '/* jshint -W109 */\niD.areaKeys = ' + stringify(areaKeys) + ';');
-
     var presetsYaml = _.cloneDeep(translations);
     _.forEach(presetsYaml.presets, function(preset) {
         preset.terms = "<translate with synonyms or related terms for '" + preset.name + "', separated by commas>"
     });
 
-    fs.writeFileSync('data/presets.yaml', YAML.dump({en: {presets: presetsYaml}}));
+    return {
+        presets: presets,
+        areaKeys: areaKeys,
+        presetsYaml: presetsYaml
+    };
 }
 
-function validateCategoryPresets() {
-    var categories = rp('categories.json'),
-        presets = rp('presets.json');
+function validateCategoryPresets(categories, presets) {
     _.forEach(categories, function(category) {
         if (category.members) {
             category.members.forEach(function(preset) {
@@ -197,7 +196,7 @@ function validateCategoryPresets() {
     });
 }
 
-function validatePresetFields() {
+function validatePresetFields(presets, fields) {
     var presets = rp('presets.json'),
         fields = rp('fields.json');
     _.forEach(presets, function(preset) {
@@ -212,13 +211,20 @@ function validatePresetFields() {
     });
 }
 
-generateCategories();
-generateFields();
-generatePresets();
+var categories = generateCategories(),
+    fields = generateFields(),
+    presets = generatePresets();
 
 // additional consistency checks
-validateCategoryPresets();
-validatePresetFields();
+validateCategoryPresets(categories, presets.presets);
+validatePresetFields(presets.presets, fields);
+
+// Save individual data files
+fs.writeFileSync('data/presets/categories.json', stringify(categories));
+fs.writeFileSync('data/presets/fields.json', stringify(fields));
+fs.writeFileSync('data/presets/presets.json', stringify(presets.presets));
+fs.writeFileSync('js/id/core/area_keys.js', '/* jshint -W109 */\niD.areaKeys = ' + stringify(presets.areaKeys) + ';');
+fs.writeFileSync('data/presets.yaml', YAML.dump({en: {presets: presets.presetsYaml}}));
 
 // Push changes from data/core.yaml into en.json
 var core = YAML.load(fs.readFileSync('data/core.yaml', 'utf8'));