diff --git a/dist/server/config.js b/dist/server/config.js
index 7f108488d202..6e040f40d98a 100644
--- a/dist/server/config.js
+++ b/dist/server/config.js
@@ -98,8 +98,16 @@ var logger = console;
 
 function addJsonLoaderIfNotAvailable(config) {
   var jsonLoaderExists = config.module.loaders.reduce(function (value, loader) {
-    return value || [].concat(loader.test).some(function (regex) {
-      return regex.test('my_package.json');
+    return value || [].concat(loader.test).some(function (matcher) {
+      var isRegex = matcher instanceof RegExp;
+      var testString = 'my_package.json';
+      if (isRegex) {
+        return matcher.test(testString);
+      }
+      if (typeof matcher === 'function') {
+        return matcher(testString);
+      }
+      return false;
     });
   }, false);
 
diff --git a/src/server/config.js b/src/server/config.js
index 84cba3cd3d34..6cc8b126d4bb 100644
--- a/src/server/config.js
+++ b/src/server/config.js
@@ -11,7 +11,17 @@ const logger = console;
 export function addJsonLoaderIfNotAvailable(config) {
   const jsonLoaderExists = config.module.loaders.reduce(
     (value, loader) => {
-      return value || [].concat(loader.test).some(regex => regex.test('my_package.json'));
+      return value || [].concat(loader.test).some((matcher) => {
+        const isRegex = matcher instanceof RegExp;
+        const testString = 'my_package.json';
+        if (isRegex) {
+          return matcher.test(testString);
+        }
+        if (typeof matcher === 'function') {
+          return matcher(testString);
+        }
+        return false;
+      });
     },
     false
   );