diff --git a/test/unit/EthabiTest.php b/test/unit/EthabiTest.php
index d056f6b..4ce7284 100644
--- a/test/unit/EthabiTest.php
+++ b/test/unit/EthabiTest.php
@@ -182,6 +182,18 @@ class EthabiTest extends TestCase
         $this->assertEquals($str, '0x095ea7b334ae44009aa867bfb386f5c3b4b443ac6f0ee573fa91c4608fbadfba');
     }
 
+    /**
+     * testEncodeParameter
+     * 
+     * @return void
+     */
+    public function testEncodeParameter()
+    {
+        $abi = $this->abi;
+
+        $this->assertEquals('0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff', $abi->encodeParameter('int256', '-1'));
+    }
+
     /**
      * testEncodeParameters
      *