diff --git a/tests/unit/Spanner/ValueMapperTest.php b/tests/unit/Spanner/ValueMapperTest.php
index e1e02b089df2..34afd9f40be9 100644
--- a/tests/unit/Spanner/ValueMapperTest.php
+++ b/tests/unit/Spanner/ValueMapperTest.php
@@ -32,8 +32,6 @@
 class ValueMapperTest extends \PHPUnit_Framework_TestCase
 {
     use GrpcTestTrait;
-    
-    const FORMAT_TEST_VALUE = 'abc';
 
     private $mapper;