diff --git a/build/code-sniffer-ruleset-tests.xml b/build/code-sniffer-ruleset-tests.xml
index c3694258..f30722f7 100644
--- a/build/code-sniffer-ruleset-tests.xml
+++ b/build/code-sniffer-ruleset-tests.xml
@@ -16,6 +16,9 @@
    <exclude name="PEAR.Commenting.FileComment.MissingTag" />
    <exclude name="PEAR.Commenting.FileComment.MissingVersion" />
    <exclude name="PEAR.Commenting.FileComment.SpacingBeforeTags" />
+
+   <!-- Test classes do not have to be namespaced. -->
+   <exclude name="PSR1.Classes.ClassDeclaration.MissingNamespace" />
  </rule>
 
 </ruleset>
diff --git a/build/code-sniffer-ruleset.xml b/build/code-sniffer-ruleset.xml
index 963c2892..f6bf92c7 100644
--- a/build/code-sniffer-ruleset.xml
+++ b/build/code-sniffer-ruleset.xml
@@ -48,6 +48,15 @@
  <!-- Constructors MUST be called __construct() instead of after the class. -->
  <rule ref="Generic.NamingConventions.ConstructorName" />
 
+ <!-- Classes etc. MUST be namespaced -->
+ <rule ref="PSR1.Classes.ClassDeclaration.MissingNamespace" />
+
+ <!-- A file MUST not contain more than one class/interface -->
+ <rule ref="PSR1.Classes.ClassDeclaration.MultipleClasses" />
+
+ <!-- Files containing classes MUST not have any side-effects -->
+ <rule ref="PSR1.Files.SideEffects.FoundWithSymbols" />
+
  <!-- Each file MUST end with exactly one newline character -->
  <rule ref="PSR2.Files.EndFileNewline" />
 
diff --git a/tests/Unit/Crypt/AES/TestCase.php b/tests/Unit/Crypt/AES/TestCase.php
index 8a222c4e..fa789bb0 100644
--- a/tests/Unit/Crypt/AES/TestCase.php
+++ b/tests/Unit/Crypt/AES/TestCase.php
@@ -9,12 +9,12 @@ use phpseclib\Crypt\AES;
 use phpseclib\Crypt\Base;
 use phpseclib\Crypt\Rijndael;
 
-require_once 'Crypt/AES.php';
-
 abstract class Unit_Crypt_AES_TestCase extends PhpseclibTestCase
 {
     static public function setUpBeforeClass()
     {
+        include_once 'Crypt/AES.php';
+
         parent::setUpBeforeClass();
 
         self::reRequireFile('Crypt/Rijndael.php');
diff --git a/tests/Unit/Math/BigInteger/TestCase.php b/tests/Unit/Math/BigInteger/TestCase.php
index f84c852f..fae3eb0c 100644
--- a/tests/Unit/Math/BigInteger/TestCase.php
+++ b/tests/Unit/Math/BigInteger/TestCase.php
@@ -5,12 +5,12 @@
  * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
  */
 
-require_once 'Math/BigInteger.php';
-
 abstract class Unit_Math_BigInteger_TestCase extends PhpseclibTestCase
 {
     static public function setUpBeforeClass()
     {
+        include_once 'Math/BigInteger.php';
+
         parent::setUpBeforeClass();
 
         self::reRequireFile('Math/BigInteger.php');