diff --git a/lib/Doctrine/KeyValueStore/InvalidArgumentException.php b/lib/Doctrine/KeyValueStore/InvalidArgumentException.php
new file mode 100644
index 0000000..1d42f93
--- /dev/null
+++ b/lib/Doctrine/KeyValueStore/InvalidArgumentException.php
@@ -0,0 +1,48 @@
+<?php
+/*
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This software consists of voluntary contributions made by many individuals
+ * and is licensed under the MIT license. For more information, see
+ * <http://www.doctrine-project.org>.
+ */
+
+namespace Doctrine\KeyValueStore;
+
+
+class InvalidArgumentException extends KeyValueStoreException
+{
+    public static function invalidType($name, $expectedType, &$actual)
+    {
+        return new static(
+            sprintf('The %s must be a %s, got "%s" instead.', $name, $expectedType, gettype($actual)),
+            0
+        );
+    }
+
+    public static function invalidLength($name, $min, $max)
+    {
+        return new static(
+            sprintf('The %s must be at least %d but no more than %d chars.', $name, $min, $max),
+            0
+        );
+    }
+
+    public static function invalidTableName($name)
+    {
+        return new static(
+            sprintf('Invalid table name: %s', $name),
+            0
+        );
+    }
+}
diff --git a/lib/Doctrine/KeyValueStore/Storage/AmazonDynamoDbStorage.php b/lib/Doctrine/KeyValueStore/Storage/AmazonDynamoDbStorage.php
index fcf5e7f..a2bbcbc 100644
--- a/lib/Doctrine/KeyValueStore/Storage/AmazonDynamoDbStorage.php
+++ b/lib/Doctrine/KeyValueStore/Storage/AmazonDynamoDbStorage.php
@@ -22,6 +22,7 @@
 use Aws\DynamoDb\DynamoDbClient;
 use Aws\DynamoDb\Marshaler;
 use Doctrine\KeyValueStore\NotFoundException;
+use Doctrine\KeyValueStore\InvalidArgumentException;
 
 class AmazonDynamoDbStorage implements Storage
 {
@@ -82,14 +83,12 @@ public function __construct(
     private function  validateKeyName($name)
     {
         if (!is_string($name)) {
-            throw new \InvalidArgumentException(
-                sprintf('The key must be a string, got "%s" instead.', gettype($name))
-            );
+            throw InvalidArgumentException::invalidType('key', 'string', $name);
         }
 
         $len = strlen($name);
         if ($len > 255 || $len < 1) {
-            throw new \InvalidArgumentException('The name must not exceed 255 bytes.');
+            throw InvalidArgumentException::invalidLength('name', 1, 255);
         }
     }
 
@@ -105,13 +104,11 @@ private function  validateKeyName($name)
     private function  validateTableName($name)
     {
         if (!is_string($name)) {
-            throw new \InvalidArgumentException(
-                sprintf('The key must be a string, got "%s" instead.', gettype($name))
-            );
+            throw InvalidArgumentException::invalidType('key', 'string', $name);
         }
 
         if (!preg_match('/^[a-z0-9_.-]{3,255}$/i', $name)) {
-            throw new \InvalidArgumentException('Invalid DynamoDB table name.');
+            throw InvalidArgumentException::invalidTableName($name);
         }
     }
 
@@ -146,7 +143,7 @@ public function getDefaultKeyName()
      *
      * @throws \InvalidArgumentException When the key or table name is invalid.
      */
-    public function setKeyForTable($table, $key)
+    private function setKeyForTable($table, $key)
     {
         $this->validateTableName($table);
         $this->validateKeyName($key);
diff --git a/tests/Doctrine/Tests/KeyValueStore/Storage/AmazonDynamoDbTest.php b/tests/Doctrine/Tests/KeyValueStore/Storage/AmazonDynamoDbTest.php
index 57d5c51..b8085bb 100644
--- a/tests/Doctrine/Tests/KeyValueStore/Storage/AmazonDynamoDbTest.php
+++ b/tests/Doctrine/Tests/KeyValueStore/Storage/AmazonDynamoDbTest.php
@@ -51,7 +51,7 @@ public function testThatTableKeysInitiallyEmpty()
     }
 
     /**
-     * @expectedException \InvalidArgumentException
+     * @expectedException \Doctrine\KeyValueStore\KeyValueStoreException
      * @expectedExceptionMessage The key must be a string, got "array" instead.
      */
     public function testDefaultKeyCannotBeSomethingOtherThanString()
@@ -61,7 +61,7 @@ public function testDefaultKeyCannotBeSomethingOtherThanString()
     }
 
     /**
-     * @expectedException \InvalidArgumentException
+     * @expectedException \Doctrine\KeyValueStore\KeyValueStoreException
      * @expectedExceptionMessage The key must be a string, got "object" instead.
      */
     public function testTableKeysMustAllBeStringsOrElse()
@@ -71,8 +71,8 @@ public function testTableKeysMustAllBeStringsOrElse()
     }
 
     /**
-     * @expectedException \InvalidArgumentException
-     * @expectedExceptionMessage The name must not exceed 255 bytes.
+     * @expectedException \Doctrine\KeyValueStore\KeyValueStoreException
+     * @expectedExceptionMessage The name must be at least 1 but no more than 255 chars.
      */
     public function testKeyNameMustBeUnder255Bytes()
     {
@@ -101,16 +101,28 @@ public function validTableNames()
         ];
     }
 
+    private function invokeMethod($methodName, $obj, array $args = null)
+    {
+        $relf = new \ReflectionObject($obj);
+        $method = $relf->getMethod($methodName);
+        $method->setAccessible(true);
+
+        if ($args) {
+            return $method->invokeArgs($obj, $args);
+        }
+
+        return $method->invoke($obj);
+    }
+
     /**
      * @dataProvider invalidTableNames
-     * @expectedException \InvalidArgumentException
-     * @expectedExceptionMessage Invalid DynamoDB table name.
+     * @expectedException \Doctrine\KeyValueStore\KeyValueStoreException
      */
     public function testTableNameValidatesAgainstInvalidTableNames($tableName)
     {
         $client = $this->getDynamoDbMock();
         $storage = new AmazonDynamoDbStorage($client);
-        $storage->setKeyForTable($tableName, 'Id');
+        $this->invokeMethod('setKeyForTable', $storage, [$tableName, 'Id']);
     }
 
     /**
@@ -120,7 +132,7 @@ public function testTableNameValidatesAgainstValidTableNames($tableName)
     {
         $client = $this->getDynamoDbMock();
         $storage = new AmazonDynamoDbStorage($client);
-        $storage->setKeyForTable($tableName, 'Id');
+        $this->invokeMethod('setKeyForTable', $storage, [$tableName, 'Id']);
 
         $this->assertAttributeSame([$tableName => 'Id'], 'tableKeys', $storage);
     }
@@ -129,8 +141,8 @@ public function testThatYouCanHaveMultipleTablesWithOverrides()
     {
         $client = $this->getDynamoDbMock();
         $storage = new AmazonDynamoDbStorage($client);
-        $storage->setKeyForTable('Aaa', '2');
-        $storage->setKeyForTable('Bbb', '1');
+        $this->invokeMethod('setKeyForTable', $storage, ['Aaa', '2']);
+        $this->invokeMethod('setKeyForTable', $storage, ['Bbb', '1']);
 
         $this->assertAttributeSame(['Aaa' => '2', 'Bbb' => '1'], 'tableKeys', $storage);
     }
@@ -162,10 +174,7 @@ public function testThatSomeStorageHasDifferentKey()
 
         $storage = new AmazonDynamoDbStorage($client, null, 'sauce', ['this' => 'that', 'yolo' => 'now']);
 
-        $r = new \ReflectionObject($storage);
-        $method = $r->getMethod('prepareKey');
-        $method->setAccessible(true);
-        $this->assertSame(['that' => ['N' => '111']], $method->invoke($storage, 'this', 111));
+        $this->assertSame(['that' => ['N' => '111']], $this->invokeMethod('prepareKey', $storage, ['this', 111]));
     }
 
     public function testThatSomeStorageUsesDefaultKey()
@@ -174,10 +183,7 @@ public function testThatSomeStorageUsesDefaultKey()
 
         $storage = new AmazonDynamoDbStorage($client, null, 'sauce', ['this' => 'that', 'yolo' => 'now']);
 
-        $r = new \ReflectionObject($storage);
-        $method = $r->getMethod('prepareKey');
-        $method->setAccessible(true);
-        $this->assertSame(['sauce' => ['S' => 'hello']], $method->invoke($storage, 'MyTable', "hello"));
+        $this->assertSame(['sauce' => ['S' => 'hello']], $this->invokeMethod('prepareKey', $storage, ['MyTable', "hello"]));
     }
 
     public function testInsertingCallsAPutItem()