diff --git a/src/Php/MagicMethodDetector.php b/src/Php/MagicMethodDetector.php
index 46c95754..a6863257 100644
--- a/src/Php/MagicMethodDetector.php
+++ b/src/Php/MagicMethodDetector.php
@@ -13,47 +13,58 @@ use PhpParser\NodeAbstract;
 
 trait MagicMethodDetector
 {
+    protected function checkArgType(string $givenType, string $expectType, bool $canBeVar = true): bool
+    {
+        if ($canBeVar and $givenType == self::TYPE_VAR) {
+            return true;
+        }
+        return $givenType == $expectType;
+    }
+
     public function checkRequiredArgNum(string $name, MethodDef $methodDef, NodeAbstract $v): void
     {
+        $argInfoList = $methodDef->functionDef->argInfoList;
+        $returnType = $methodDef->functionDef->returnType;
+
         if ($name == '__call' or $name == '__callStatic' or $name == '__set') {
-            if (count($methodDef->functionDef->argInfoList) != 2) {
+            if (count($argInfoList) != 2) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take exactly 2 arguments");
             }
-            if ($methodDef->functionDef->argInfoList[0]->type and $methodDef->functionDef->argInfoList[0]->type != self::TYPE_STR) {
+            if (!$this->checkArgType($argInfoList[0]->type, self::TYPE_STR)) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take string as argument");
             }
         } elseif ($name == '__get') {
-            if (count($methodDef->functionDef->argInfoList) != 1) {
+            if (count($argInfoList) != 1) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take exactly 1 argument");
             }
         } elseif ($name == '__toString') {
-            if (!$methodDef->functionDef->returnType or $methodDef->functionDef->returnType != self::TYPE_STR) {
+            if (!$returnType or $returnType != self::TYPE_STR) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return string");
             }
         } elseif ($name == '__serialize') {
-            if (!$methodDef->functionDef->returnType or $methodDef->functionDef->returnType != self::TYPE_ARRAY) {
+            if (!$returnType or $returnType != self::TYPE_ARRAY) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return array");
             }
         } elseif ($name == '__unserialize') {
-            if (count($methodDef->functionDef->argInfoList) != 1) {
+            if (count($argInfoList) != 1) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take exactly 1 argument");
-            } elseif (!$methodDef->functionDef->argInfoList[0]->type or $methodDef->functionDef->argInfoList[0]->type != self::TYPE_ARRAY) {
+            } elseif (!$argInfoList[0]->type or $argInfoList[0]->type != self::TYPE_ARRAY) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take array as argument");
             }
         } elseif ($name == '__isset' or $name == '__unset' or $name == '__set_state') {
-            if (count($methodDef->functionDef->argInfoList) != 1) {
+            if (count($argInfoList) != 1) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take exactly 1 argument");
             }
-            if (!$methodDef->functionDef->argInfoList[0]->type or $methodDef->functionDef->argInfoList[0]->type != self::TYPE_STR) {
+            if (!$argInfoList[0]->type or $argInfoList[0]->type != self::TYPE_STR) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must take string as argument");
             }
             if ($name == '__set_state') {
-                if (!$methodDef->functionDef->returnType or $methodDef->functionDef->returnType != self::TYPE_ARRAY) {
+                if (!$returnType or $returnType != self::TYPE_ARRAY) {
                     $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return array");
                 }
             }
         } elseif ($name == '__debugInfo') {
-            if (!$methodDef->functionDef->returnType or $methodDef->functionDef->returnType != self::TYPE_ARRAY) {
+            if (!$returnType or $returnType != self::TYPE_ARRAY) {
                 $this->fatalError($v, 'Method ' . $this->class . "::{$name}() must return array");
             }
         }