diff --git a/src/PHPCR/Util/QOM/BaseSqlGenerator.php b/src/PHPCR/Util/QOM/BaseSqlGenerator.php
index 1cbb392..dca2e2b 100644
--- a/src/PHPCR/Util/QOM/BaseSqlGenerator.php
+++ b/src/PHPCR/Util/QOM/BaseSqlGenerator.php
@@ -83,7 +83,7 @@ public function evalOr($constraint1, $constraint2)
      */
     public function evalNot($constraint)
     {
-        return "NOT $constraint";
+        return "(NOT $constraint)";
     }
 
     /**
diff --git a/tests/PHPCR/Tests/Util/QOM/BaseSqlGeneratorTest.php b/tests/PHPCR/Tests/Util/QOM/BaseSqlGeneratorTest.php
new file mode 100644
index 0000000..d5984db
--- /dev/null
+++ b/tests/PHPCR/Tests/Util/QOM/BaseSqlGeneratorTest.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace PHPCR\Tests\Util\QOM;
+
+use PHPCR\Util\QOM\Sql1Generator;
+use PHPCR\Util\ValueConverter;
+
+abstract class BaseSqlGeneratorTest extends \PHPUnit_Framework_TestCase
+{
+    public function testNot()
+    {
+        $string = $this->generator->evalNot("foo = bar");
+        $this->assertSame("(NOT foo = bar)", $string);
+    }
+}
diff --git a/tests/PHPCR/Tests/Util/QOM/Sql2GeneratorTest.php b/tests/PHPCR/Tests/Util/QOM/Sql2GeneratorTest.php
index e5cbc75..83f40a7 100644
--- a/tests/PHPCR/Tests/Util/QOM/Sql2GeneratorTest.php
+++ b/tests/PHPCR/Tests/Util/QOM/Sql2GeneratorTest.php
@@ -5,7 +5,7 @@
 use PHPCR\Util\QOM\Sql2Generator;
 use PHPCR\Util\ValueConverter;
 
-class Sql2GeneratorTest extends \PHPUnit_Framework_TestCase
+class Sql2GeneratorTest extends BaseSqlGeneratorTest
 {
     protected $generator;