diff --git a/src/Formatters/PrivateFormatter.php b/src/Formatters/PrivateFormatter.php
new file mode 100644
index 0000000..4420f58
--- /dev/null
+++ b/src/Formatters/PrivateFormatter.php
@@ -0,0 +1,36 @@
+<?php
+
+/**
+ * This file is part of web3.php package.
+ *
+ * (c) Kuan-Cheng,Lai <alk03073135@gmail.com>
+ *
+ * @author Peter Lai <alk03073135@gmail.com>
+ * @license MIT
+ */
+
+namespace Web3\Formatters;
+
+use InvalidArgumentException;
+use Web3\Utils;
+use Web3\Formatters\IFormatter;
+
+class PrivateFormatter implements IFormatter
+{
+    /**
+     * format
+     *
+     * @param mixed $value
+     * @return string
+     */
+    public static function format($value)
+    {
+        $value = Utils::toString($value);
+        $value = mb_strtolower($value);
+
+        if (Utils::isZeroPrefixed($value)) {
+            $value = Utils::stripZero($value);
+        }
+        return $value;
+    }
+}
diff --git a/src/Methods/Personal/ImportRawKey.php b/src/Methods/Personal/ImportRawKey.php
index f2c6722..63fb71e 100644
--- a/src/Methods/Personal/ImportRawKey.php
+++ b/src/Methods/Personal/ImportRawKey.php
@@ -16,6 +16,7 @@ use Web3\Methods\EthMethod;
 use Web3\Validators\PrivateValidator;
 use Web3\Validators\StringValidator;
 use Web3\Formatters\StringFormatter;
+use Web3\Formatters\PrivateFormatter;
 
 class ImportRawKey extends EthMethod
 {
@@ -34,7 +35,7 @@ class ImportRawKey extends EthMethod
      * @var array
      */
     protected $inputFormatters = [
-        PrivateValidator::class, StringFormatter::class
+        PrivateFormatter::class, StringFormatter::class
     ];
 
     /**
diff --git a/src/Validators/PrivateValidator.php b/src/Validators/PrivateValidator.php
index 57bfe8d..5656c22 100644
--- a/src/Validators/PrivateValidator.php
+++ b/src/Validators/PrivateValidator.php
@@ -26,6 +26,6 @@ class PrivateValidator
         if (!is_string($value)) {
             return false;
         }
-        return (preg_match('/^[a-fA-F0-9]{64}$/', $value) >= 1);
+        return (preg_match('/^(0x)?[a-fA-F0-9]{64}$/', $value) >= 1);
     }
 }