diff --git a/INSTALL b/INSTALL
index 87e61012..fb672e82 100644
--- a/INSTALL
+++ b/INSTALL
@@ -168,20 +168,11 @@ Standalone version
     
         require '/path/to/HTMLPurifier.standalone.php';
     
-    This is equivalent to including HTMLPurifier.includes.php, but no
-    include path changes are necessary unless you want to use optional
-    classes. If you *do* want the optional classes, you need to add
-    HTML Purifier's source directory to your path. This will vary:
-    
-        * If you downloaded the htmlpurifier-x.y.z-standalone
-          distribution, you'll notice that the rest of the library is
-          missing; add standalone/ to your include path.
-        
-        * If you generated the standalone file yourself, the
-          standalone/ directory will also exist with the relevant
-          optional classes, but you can also set library/ to your path
-          and things will still work properly (in theory, a file in both
-          places should be equivalent).
+    This is equivalent to including HTMLPurifier.includes.php, except that
+    the contents of standalone/ will be added to your path. To override this
+    behavior, specify a new HTMLPURIFIER_PREFIX where standalone files can
+    be found (usually, this will be one directory up, the "true" library
+    directory in full distributions). Don't forget to set your path too!
     
     The autoloader can be added to the end to ensure the classes are
     loaded when necessary; otherwise you can manually include them.
diff --git a/tests/HTMLPurifier/PHPT/loading/_autoload.inc b/tests/HTMLPurifier/PHPT/loading/_autoload.inc
new file mode 100644
index 00000000..45023695
--- /dev/null
+++ b/tests/HTMLPurifier/PHPT/loading/_autoload.inc
@@ -0,0 +1,10 @@
+<?php
+
+/**
+ * Tests if autoloading for HTML Purifier is enabled. If all tests pass,
+ * output is blank.
+ */
+
+assert("!in_array(realpath('../library/HTMLPurifier/Filter/YouTube.php'), get_included_files())");
+new HTMLPurifier_Filter_YouTube();
+assert(" in_array(realpath('../library/HTMLPurifier.autoload.php'), get_included_files())");
diff --git a/tests/HTMLPurifier/PHPT/loading/_no-autoload.inc b/tests/HTMLPurifier/PHPT/loading/_no-autoload.inc
new file mode 100644
index 00000000..24bce6f5
--- /dev/null
+++ b/tests/HTMLPurifier/PHPT/loading/_no-autoload.inc
@@ -0,0 +1,15 @@
+<?php
+
+/**
+ * Tests if autoloading is off in HTML Purifier. If all tests pass, no output.
+ */
+
+if (function_exists('spl_autoload_register')) {
+    $__v = spl_autoload_functions();
+    assert('$__v == false || !in_array(array("HTMLPurifier_Bootstrap", "autoload"), $__v)');
+} else {
+    if (function_exists('__autoload')) {
+        $__r = new ReflectionFunction('__autoload');
+        assert('$__r->getFileName() != realpath("../library/HTMLPurifier.autoload.php")');
+    }
+}
diff --git a/tests/HTMLPurifier/PHPT/loading/auto-includes.phpt b/tests/HTMLPurifier/PHPT/loading/auto-includes.phpt
index 69327e31..2768cd04 100644
--- a/tests/HTMLPurifier/PHPT/loading/auto-includes.phpt
+++ b/tests/HTMLPurifier/PHPT/loading/auto-includes.phpt
@@ -2,8 +2,9 @@
 HTMLPurifier.auto.php and HTMLPurifier.includes.php loading test
 --FILE--
 <?php
-require_once '../library/HTMLPurifier.path.php';
-require_once 'HTMLPurifier.includes.php';
+require '../library/HTMLPurifier.path.php';
+require 'HTMLPurifier.includes.php';
+require 'HTMLPurifier/PHPT/loading/_no-autoload.inc';
 $config = HTMLPurifier_Config::createDefault();
 $purifier = new HTMLPurifier($config);
 echo $purifier->purify('<b>Salsa!');
diff --git a/tests/HTMLPurifier/PHPT/loading/auto-with-autoload.phpt b/tests/HTMLPurifier/PHPT/loading/auto-with-autoload.phpt
index bb2dfa72..a446f87b 100644
--- a/tests/HTMLPurifier/PHPT/loading/auto-with-autoload.phpt
+++ b/tests/HTMLPurifier/PHPT/loading/auto-with-autoload.phpt
@@ -12,7 +12,8 @@ function __autoload($class) {
     eval("class $class {}");
 }
 
-require_once '../library/HTMLPurifier.auto.php';
+require '../library/HTMLPurifier.auto.php';
+require 'HTMLPurifier/PHPT/loading/_autoload.inc';
 $config = HTMLPurifier_Config::createDefault();
 $purifier = new HTMLPurifier($config);
 echo $purifier->purify('<b>Salsa!') . PHP_EOL;
diff --git a/tests/HTMLPurifier/PHPT/loading/auto-with-spl-autoload.phpt b/tests/HTMLPurifier/PHPT/loading/auto-with-spl-autoload.phpt
index 23c7f46f..dfc937a0 100644
--- a/tests/HTMLPurifier/PHPT/loading/auto-with-spl-autoload.phpt
+++ b/tests/HTMLPurifier/PHPT/loading/auto-with-spl-autoload.phpt
@@ -12,7 +12,8 @@ function __autoload($class) {
     eval("class $class {}");
 }
 
-require_once '../library/HTMLPurifier.auto.php';
+require '../library/HTMLPurifier.auto.php';
+require 'HTMLPurifier/PHPT/loading/_autoload.inc';
 $config = HTMLPurifier_Config::createDefault();
 $purifier = new HTMLPurifier($config);
 echo $purifier->purify('<b>Salsa!') . PHP_EOL;
diff --git a/tests/HTMLPurifier/PHPT/loading/auto-without-spl-autoload.phpt b/tests/HTMLPurifier/PHPT/loading/auto-without-spl-autoload.phpt
index a05a2fe1..be56f132 100644
--- a/tests/HTMLPurifier/PHPT/loading/auto-without-spl-autoload.phpt
+++ b/tests/HTMLPurifier/PHPT/loading/auto-without-spl-autoload.phpt
@@ -8,11 +8,11 @@ if (function_exists('spl_autoload_register')) {
 --FILE--
 <?php
 assert("!function_exists('__autoload')");
-require_once '../library/HTMLPurifier.auto.php';
+require '../library/HTMLPurifier.auto.php';
+require 'HTMLPurifier/PHPT/loading/_autoload.inc';
 $config = HTMLPurifier_Config::createDefault();
 $purifier = new HTMLPurifier($config);
 echo $purifier->purify('<b>Salsa!') . PHP_EOL;
-assert("function_exists('__autoload')");
 
 --EXPECT--
 <b>Salsa!</b>
diff --git a/tests/HTMLPurifier/PHPT/loading/auto-without-spl-with-autoload.phpt b/tests/HTMLPurifier/PHPT/loading/auto-without-spl-with-autoload.phpt
new file mode 100644
index 00000000..7bf6612b
--- /dev/null
+++ b/tests/HTMLPurifier/PHPT/loading/auto-without-spl-with-autoload.phpt
@@ -0,0 +1,20 @@
+--TEST--
+HTMLPurifier.auto.php without spl_autoload_register but with userland
+__autoload() defined test
+--SKIPIF--
+<?php
+if (function_exists('spl_autoload_register')) {
+    echo "skip - spl_autoload_register() available";
+}
+--FILE--
+<?php
+function __autoload($class) {
+    echo "Autoloading $class..." . PHP_EOL;
+    eval("class $class {}");
+}
+require '../library/HTMLPurifier.auto.php';
+require 'HTMLPurifier/PHPT/loading/_no-autoload.inc';
+$purifier = new HTMLPurifier();
+
+--EXPECT--
+Autoloading HTMLPurifier...
diff --git a/tests/HTMLPurifier/PHPT/loading/auto.phpt b/tests/HTMLPurifier/PHPT/loading/auto.phpt
index c83319ee..bd78f3d9 100644
--- a/tests/HTMLPurifier/PHPT/loading/auto.phpt
+++ b/tests/HTMLPurifier/PHPT/loading/auto.phpt
@@ -2,7 +2,8 @@
 HTMLPurifier.auto.php loading test
 --FILE--
 <?php
-require_once '../library/HTMLPurifier.auto.php';
+require '../library/HTMLPurifier.auto.php';
+require 'HTMLPurifier/PHPT/loading/_autoload.inc';
 $config = HTMLPurifier_Config::createDefault();
 $purifier = new HTMLPurifier($config);
 echo $purifier->purify('<b>Salsa!');
diff --git a/tests/HTMLPurifier/PHPT/loading/path-includes-autoload.phpt b/tests/HTMLPurifier/PHPT/loading/path-includes-autoload.phpt
new file mode 100644
index 00000000..a6cb59e3
--- /dev/null
+++ b/tests/HTMLPurifier/PHPT/loading/path-includes-autoload.phpt
@@ -0,0 +1,14 @@
+--TEST--
+HTMLPurifier.path.php, HTMLPurifier.includes.php and HTMLPurifier.autoload.php loading test
+--FILE--
+<?php
+require '../library/HTMLPurifier.path.php';
+require 'HTMLPurifier.includes.php';
+require 'HTMLPurifier.autoload.php';
+require 'HTMLPurifier/PHPT/loading/_autoload.inc';
+$config = HTMLPurifier_Config::createDefault();
+$purifier = new HTMLPurifier($config);
+echo $purifier->purify('<b>Salsa!');
+
+--EXPECT--
+<b>Salsa!</b>
diff --git a/tests/HTMLPurifier/PHPT/loading/path-includes.phpt b/tests/HTMLPurifier/PHPT/loading/path-includes.phpt
new file mode 100644
index 00000000..2c703ca3
--- /dev/null
+++ b/tests/HTMLPurifier/PHPT/loading/path-includes.phpt
@@ -0,0 +1,12 @@
+--TEST--
+HTMLPurifier.path.php and HTMLPurifier.includes.php loading test
+--FILE--
+<?php
+require '../library/HTMLPurifier.path.php';
+require 'HTMLPurifier.includes.php';
+require 'HTMLPurifier/PHPT/loading/_no-autoload.inc';
+$config = HTMLPurifier_Config::createDefault();
+$purifier = new HTMLPurifier($config);
+echo $purifier->purify('<b>Salsa!');
+--EXPECT--
+<b>Salsa!</b>
diff --git a/tests/HTMLPurifier/PHPT/loading/standalone-autoload.phpt b/tests/HTMLPurifier/PHPT/loading/standalone-autoload.phpt
new file mode 100644
index 00000000..bad3647b
--- /dev/null
+++ b/tests/HTMLPurifier/PHPT/loading/standalone-autoload.phpt
@@ -0,0 +1,12 @@
+--TEST--
+HTMLPurifier.standalone.php loading test
+--FILE--
+<?php
+require '../library/HTMLPurifier.standalone.php';
+require '../library/HTMLPurifier.autoload.php';
+require 'HTMLPurifier/PHPT/loading/_autoload.inc';
+$config = HTMLPurifier_Config::createDefault();
+$purifier = new HTMLPurifier($config);
+echo $purifier->purify('<b>Salsa!');
+--EXPECT--
+<b>Salsa!</b>
diff --git a/tests/HTMLPurifier/PHPT/loading/standalone-with-prefix.phpt b/tests/HTMLPurifier/PHPT/loading/standalone-with-prefix.phpt
new file mode 100644
index 00000000..d1ee2bdb
--- /dev/null
+++ b/tests/HTMLPurifier/PHPT/loading/standalone-with-prefix.phpt
@@ -0,0 +1,15 @@
+--TEST--
+HTMLPurifier.standalone.php with HTMLPURIFIER_PREFIX loading test
+--FILE--
+<?php
+define('HTMLPURIFIER_PREFIX', realpath('../library'));
+require '../library/HTMLPurifier.path.php';
+require 'HTMLPurifier.standalone.php';
+require 'HTMLPurifier/Filter/YouTube.php';
+require 'HTMLPurifier/PHPT/loading/_no-autoload.inc';
+$config = HTMLPurifier_Config::createDefault();
+$purifier = new HTMLPurifier($config);
+echo $purifier->purify('<b>Salsa!');
+assert('in_array(realpath("../library/HTMLPurifier/Filter/YouTube.php"), get_included_files())');
+--EXPECT--
+<b>Salsa!</b>
diff --git a/tests/HTMLPurifier/PHPT/loading/standalone.phpt b/tests/HTMLPurifier/PHPT/loading/standalone.phpt
index ab9a5fb5..7fb0a3bc 100644
--- a/tests/HTMLPurifier/PHPT/loading/standalone.phpt
+++ b/tests/HTMLPurifier/PHPT/loading/standalone.phpt
@@ -2,9 +2,12 @@
 HTMLPurifier.standalone.php loading test
 --FILE--
 <?php
-require_once '../library/HTMLPurifier.standalone.php';
+require '../library/HTMLPurifier.standalone.php';
+require 'HTMLPurifier/Filter/YouTube.php';
+require 'HTMLPurifier/PHPT/loading/_no-autoload.inc';
 $config = HTMLPurifier_Config::createDefault();
 $purifier = new HTMLPurifier($config);
 echo $purifier->purify('<b>Salsa!');
+assert('in_array(realpath("../library/standalone/HTMLPurifier/Filter/YouTube.php"), get_included_files())');
 --EXPECT--
 <b>Salsa!</b>