diff --git a/src/PhpSpreadsheet/Calculation.php b/src/PhpSpreadsheet/Calculation.php
index 51edf37c..930bf9ea 100644
--- a/src/PhpSpreadsheet/Calculation.php
+++ b/src/PhpSpreadsheet/Calculation.php
@@ -2039,7 +2039,7 @@ class Calculation
 
     private static function loadLocales()
     {
-        $localeFileDirectory = PHPSPREADSHEET_ROOT . 'PhpSpreadsheet/locale/';
+        $localeFileDirectory = __DIR__ . '/locale/';
         foreach (glob($localeFileDirectory . '/*', GLOB_ONLYDIR) as $filename) {
             $filename = substr($filename, strlen($localeFileDirectory) + 1);
             if ($filename != 'en') {
@@ -2269,10 +2269,10 @@ class Calculation
             //    Default is English, if user isn't requesting english, then read the necessary data from the locale files
             if ($locale != 'en_us') {
                 //    Search for a file with a list of function names for locale
-                $functionNamesFile = PHPSPREADSHEET_ROOT . 'PhpSpreadsheet' . DIRECTORY_SEPARATOR . 'locale' . DIRECTORY_SEPARATOR . str_replace('_', DIRECTORY_SEPARATOR, $locale) . DIRECTORY_SEPARATOR . 'functions';
+                $functionNamesFile = __DIR__ . '/locale/' . str_replace('_', DIRECTORY_SEPARATOR, $locale) . DIRECTORY_SEPARATOR . 'functions';
                 if (!file_exists($functionNamesFile)) {
                     //    If there isn't a locale specific function file, look for a language specific function file
-                    $functionNamesFile = PHPSPREADSHEET_ROOT . 'PhpSpreadsheet' . DIRECTORY_SEPARATOR . 'locale' . DIRECTORY_SEPARATOR . $language . DIRECTORY_SEPARATOR . 'functions';
+                    $functionNamesFile = __DIR__ . '/locale/' . $language . DIRECTORY_SEPARATOR . 'functions';
                     if (!file_exists($functionNamesFile)) {
                         return false;
                     }
@@ -2298,9 +2298,9 @@ class Calculation
                     self::$localeBoolean['FALSE'] = self::$localeFunctions['FALSE'];
                 }
 
-                $configFile = PHPSPREADSHEET_ROOT . 'PhpSpreadsheet' . DIRECTORY_SEPARATOR . 'locale' . DIRECTORY_SEPARATOR . str_replace('_', DIRECTORY_SEPARATOR, $locale) . DIRECTORY_SEPARATOR . 'config';
+                $configFile = __DIR__ . '/locale/' . str_replace('_', DIRECTORY_SEPARATOR, $locale) . DIRECTORY_SEPARATOR . 'config';
                 if (!file_exists($configFile)) {
-                    $configFile = PHPSPREADSHEET_ROOT . 'PhpSpreadsheet' . DIRECTORY_SEPARATOR . 'locale' . DIRECTORY_SEPARATOR . $language . DIRECTORY_SEPARATOR . 'config';
+                    $configFile = __DIR__ . '/locale/' . $language . DIRECTORY_SEPARATOR . 'config';
                 }
                 if (file_exists($configFile)) {
                     $localeSettings = file($configFile, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
diff --git a/tests/PhpSpreadsheetTests/CalculationTest.php b/tests/PhpSpreadsheetTests/CalculationTest.php
index ee9aac35..8711e6ac 100644
--- a/tests/PhpSpreadsheetTests/CalculationTest.php
+++ b/tests/PhpSpreadsheetTests/CalculationTest.php
@@ -38,9 +38,9 @@ class CalculationTest extends \PHPUnit_Framework_TestCase
     /**
      * @dataProvider providerGetFunctions
      *
-     * @param mixed $category
-     * @param mixed $functionCall
-     * @param mixed $argumentCount
+     * @param string $category
+     * @param array|string $functionCall
+     * @param string $argumentCount
      */
     public function testGetFunctions($category, $functionCall, $argumentCount)
     {
@@ -60,4 +60,39 @@ class CalculationTest extends \PHPUnit_Framework_TestCase
         $this->assertTrue($calculation->isImplemented('coUNt'));
         $this->assertTrue($calculation->isImplemented('abs'));
     }
+
+    /**
+     * @dataProvider providerCanLoadAllSupportedLocales
+     *
+     * @param string $locale
+     */
+    public function testCanLoadAllSupportedLocales($locale)
+    {
+        $calculation = Calculation::getInstance();
+        $this->assertTrue($calculation->setLocale($locale));
+    }
+
+    public function providerCanLoadAllSupportedLocales()
+    {
+        return [
+            ['bg'],
+            ['cs'],
+            ['da'],
+            ['de'],
+            ['en_us'],
+            ['es'],
+            ['fi'],
+            ['fr'],
+            ['hu'],
+            ['it'],
+            ['nl'],
+            ['no'],
+            ['pl'],
+            ['pt'],
+            ['pt_br'],
+            ['ru'],
+            ['sv'],
+            ['tr'],
+        ];
+    }
 }