diff --git a/.phpunit.result.cache b/.phpunit.result.cache
new file mode 100644
index 0000000..45a0b0d
--- /dev/null
+++ b/.phpunit.result.cache
@@ -0,0 +1 @@
+{"version":1,"defects":{"Gabeta\\GsmDetector\\Test\\GsmDetectorTest::test_is_gsm":4,"Gabeta\\GsmDetector\\Test\\GsmDetectorTest::test_is_gsm_name":4,"Gabeta\\GsmDetector\\Test\\GsmDetectorTest::test_get_gsm_name":4},"times":{"Gabeta\\GsmDetector\\Test\\GsmDetectorTest::test_is_gsm":0.001,"Gabeta\\GsmDetector\\Test\\GsmDetectorTest::test_is_gsm_with_type":0,"Gabeta\\GsmDetector\\Test\\GsmDetectorTest::test_is_gsm_name":0,"Gabeta\\GsmDetector\\Test\\GsmDetectorTest::test_is_gsm_name_with_type":0,"Gabeta\\GsmDetector\\Test\\GsmDetectorTest::test_get_gsm_name":0,"Gabeta\\GsmDetector\\Test\\GsmDetectorTest::test_is_type":0}}
\ No newline at end of file
diff --git a/src/GsmDetector.php b/src/GsmDetector.php
index 81747f1..39ba1cb 100644
--- a/src/GsmDetector.php
+++ b/src/GsmDetector.php
@@ -83,7 +83,7 @@ public function isGsm($name, $value)
     {
         $gsmConfig = self::$config[$name];
 
-        $prefix = call_user_func_array('array_merge', $gsmConfig);
+        $prefix = call_user_func_array('array_merge', array_values($gsmConfig));
 
         return $this->hasValue($prefix, $value);
     }
@@ -143,7 +143,7 @@ public function isType($value, $type)
     public function getGsmName($value)
     {
         foreach (self::$config as $key => $config) {
-            $prefix = call_user_func_array('array_merge', $config);
+            $prefix = call_user_func_array('array_merge', array_values($config));
 
             if ($this->hasValue($prefix, $value)) {
                 return $key;