diff --git a/src/Eth.php b/src/Eth.php
index 071b202..386a36a 100644
--- a/src/Eth.php
+++ b/src/Eth.php
@@ -35,15 +35,28 @@ class Eth
         'eth_blockNumber' => [],
         'eth_getBalance' => [
             'params'=> [
-                AddressValidator::class,
-                TagValidator::class
+                [
+                    'validators' => AddressValidator::class,
+                ], [
+                    'default' => 'latest',
+                    'validators' => [
+                        TagValidator::class, QuantityValidator::class,
+                    ]
+                ]
             ]
         ],
         'eth_getStorageAt' => [
             'params'=> [
-                AddressValidator::class,
-                QuantityValidator::class,
-                TagValidator::class
+                [
+                    'validators' => AddressValidator::class,
+                ], [
+                    'validators' => QuantityValidator::class,
+                ], [
+                    'default' => 'latest',
+                    'validators' => [
+                        TagValidator::class, QuantityValidator::class,
+                    ]
+                ],
             ]
         ],
     ];
@@ -91,24 +104,43 @@ class Eth
             }
             $allowedMethod = $this->methods[$method];
 
-            if (isset($allowedMethod['params'])) {
-                // validate params
-                foreach ($allowedMethod['params'] as $key => $rule) {
-                    if (call_user_func([$rule, 'validate'], $arguments[$key]) === false) {
-                        throw new \RuntimeException('Wrong type of ' . $name . ' method argument ' . $key . '.');
-                    }
-                }
-            }
             if ($this->provider->isBatch) {
-                $this->provider->send($method, $arguments, null);
+                $callback = null;
             } else {
                 $callback = array_pop($arguments);
 
                 if (is_callable($callback) !== true) {
                     throw new \InvalidArgumentException('The last param must be callback function.');
                 }
-                $this->provider->send($method, $arguments, $callback);
             }
+            if (isset($allowedMethod['params']) && is_array($allowedMethod['params'])) {
+                // validate params
+                foreach ($allowedMethod['params'] as $key => $param) {
+                    if (isset($param['validators'])) {
+                        if (is_array($param['validators'])) {
+                            foreach ($param['validators'] as $rule) {
+                                if (!isset($arguments[$key]) || call_user_func([$rule, 'validate'], $arguments[$key]) === false) {
+                                    if (isset($param['default']) && !isset($arguments[$key])) {
+                                        $arguments[$key] = $param['default'];
+                                        break;
+                                    } else {
+                                        throw new \RuntimeException('Wrong type of ' . $name . ' method argument ' . $key . '.');
+                                    }
+                                }
+                            }
+                        } else {
+                            if (!isset($arguments[$key]) || call_user_func([$param['validators'], 'validate'], $arguments[$key]) === false) {
+                                if (isset($param['default']) && !isset($arguments[$key])) {
+                                    $arguments[$key] = $param['default'];
+                                } else {
+                                    throw new \RuntimeException('Wrong type of ' . $name . ' method argument ' . $key . '.');
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+            $this->provider->send($method, $arguments, $callback);
         }
     }
 
diff --git a/src/Validators/TagValidator.php b/src/Validators/TagValidator.php
index 17fcf1a..ab436d5 100644
--- a/src/Validators/TagValidator.php
+++ b/src/Validators/TagValidator.php
@@ -18,7 +18,6 @@ class TagValidator
             'latest', 'earliest', 'pending'
         ];
 
-        // maybe change in_int and preg_match future
-        return (is_int($value) || preg_match('/^0x[a-fA-f0-9]+/', $value) >= 1 || in_array($value, $tags));
+        return in_array($value, $tags);
     }
 }
\ No newline at end of file
diff --git a/src/Web3.php b/src/Web3.php
index f458835..383d603 100644
--- a/src/Web3.php
+++ b/src/Web3.php
@@ -84,23 +84,33 @@ class Web3
             }
             $allowedMethod = $this->methods[$method];
 
+            if ($this->provider->isBatch) {
+                $callback = null;
+            } else {
+                $callback = array_pop($arguments);
+
+                if (is_callable($callback) !== true) {
+                    throw new \InvalidArgumentException('The last param must be callback function.');
+                }
+            }
             if (isset($allowedMethod['params']) && is_array($allowedMethod['params'])) {
                 // validate params
                 foreach ($allowedMethod['params'] as $key => $param) {
                     if (isset($param['validators'])) {
                         if (is_array($param['validators'])) {
                             foreach ($param['validators'] as $rule) {
-                                if (call_user_func([$rule, 'validate'], $arguments[$key]) === false) {
+                                if (!isset($arguments[$key]) || call_user_func([$rule, 'validate'], $arguments[$key]) === false) {
                                     if (isset($param['default']) && !isset($arguments[$key])) {
                                         $arguments[$key] = $param['default'];
+                                        break;
                                     } else {
                                         throw new \RuntimeException('Wrong type of ' . $name . ' method argument ' . $key . '.');
                                     }
                                 }
                             }
                         } else {
-                            if (call_user_func([$param['validators'], 'validate'], $arguments[$key]) === false) {
-                                if (!isset($param['default']) && !isset($arguments[$key])) {
+                            if (!isset($arguments[$key]) || call_user_func([$param['validators'], 'validate'], $arguments[$key]) === false) {
+                                if (isset($param['default']) && !isset($arguments[$key])) {
                                     $arguments[$key] = $param['default'];
                                 } else {
                                     throw new \RuntimeException('Wrong type of ' . $name . ' method argument ' . $key . '.');
@@ -110,16 +120,7 @@ class Web3
                     }
                 }
             }
-            if ($this->provider->isBatch) {
-                $this->provider->send($method, $arguments, null);
-            } else {
-                $callback = array_pop($arguments);
-
-                if (is_callable($callback) !== true) {
-                    throw new \InvalidArgumentException('The last param must be callback function.');
-                }
-                $this->provider->send($method, $arguments, $callback);
-            }
+            $this->provider->send($method, $arguments, $callback);
         }
     }
 
diff --git a/test/unit/EthTest.php b/test/unit/EthTest.php
index c2354f7..da45d8a 100644
--- a/test/unit/EthTest.php
+++ b/test/unit/EthTest.php
@@ -208,7 +208,7 @@ class EthTest extends TestCase
     {
         $eth = $this->web3->eth;
 
-        $eth->getBalance('0x407d73d8a49eeb85d32cf465507dd71d507100c1', 'latest', function ($err, $balance) {
+        $eth->getBalance('0x407d73d8a49eeb85d32cf465507dd71d507100c1', function ($err, $balance) {
             if ($err !== null) {
                 return $this->fail($err->getMessage());
             }
@@ -229,7 +229,7 @@ class EthTest extends TestCase
     {
         $eth = $this->web3->eth;
 
-        $eth->getStorageAt('0x407d73d8a49eeb85d32cf465507dd71d507100c1', '0x0', 'latest', function ($err, $storage) {
+        $eth->getStorageAt('0x407d73d8a49eeb85d32cf465507dd71d507100c1', '0x0', function ($err, $storage) {
             if ($err !== null) {
                 return $this->fail($err->getMessage());
             }