diff --git a/library/HTMLPurifier/ConfigSchema/InterchangeBuilder.php b/library/HTMLPurifier/ConfigSchema/InterchangeBuilder.php
index 2b2c9ab4..74a53976 100644
--- a/library/HTMLPurifier/ConfigSchema/InterchangeBuilder.php
+++ b/library/HTMLPurifier/ConfigSchema/InterchangeBuilder.php
@@ -3,6 +3,9 @@
 class HTMLPurifier_ConfigSchema_InterchangeBuilder
 {
     
+    /**
+     * Used for processing DEFAULT, nothing else.
+     */
     protected $varParser;
     
     public function __construct($varParser = null) {
@@ -70,18 +73,7 @@ class HTMLPurifier_ConfigSchema_InterchangeBuilder
         }
         
         if (isset($hash['VALUE-ALIASES'])) {
-            $value_aliases = $this->evalArray($hash->offsetGet('VALUE-ALIASES'));
-            // :TODO: Build corresponding test in Validator.php
-            try {
-                foreach ($value_aliases as $alias => $real) {
-                    // might want to allow users to use a different var parser
-                    // in this case
-                    $directive->valueAliases[$this->varParser->parse($alias, $directive->type, $directive->typeAllowsNull)] =
-                        $this->varParser->parse($real, $directive->type, $directive->typeAllowsNull);
-                }
-            } catch (HTMLPurifier_VarParserException $e) {
-                throw new HTMLPurifier_ConfigSchema_Exception($e->getMessage() . " in $alias => $real in VALUE-ALIASES in directive hash '$id'");
-            }
+            $directive->valueAliases = $this->evalArray($hash->offsetGet('VALUE-ALIASES'));
         }
         
         if (isset($hash['ALIASES'])) {
diff --git a/library/HTMLPurifier/ConfigSchema/Validator.php b/library/HTMLPurifier/ConfigSchema/Validator.php
index 5130ad52..fdb7b69d 100644
--- a/library/HTMLPurifier/ConfigSchema/Validator.php
+++ b/library/HTMLPurifier/ConfigSchema/Validator.php
@@ -79,16 +79,67 @@ class HTMLPurifier_ConfigSchema_Validator
         $this->validateId($d->id);
         $this->with($d, 'description')
             ->assertNotEmpty();
+        
+        // BEGIN - handled by InterchangeBuilder
         $this->with($d, 'type')
-            ->assertNotEmpty(); // handled by InterchangeBuilder
-        // Much stricter default check, since we're using the base implementation.
-        // handled by InterchangeBuilder
+            ->assertNotEmpty();
+        $this->with($d, 'typeAllowsNull')
+            ->assertIsBool();
         try {
+            // This also tests validity of $d->type
             $this->parser->parse($d->default, $d->type, $d->typeAllowsNull);
         } catch (HTMLPurifier_VarParserException $e) {
             $this->error('default', 'had error: ' . $e->getMessage());
         }
+        // END - handled by InterchangeBuilder
         
+        if (!is_null($d->allowed) || !empty($d->valueAliases)) {
+            // allowed and valueAliases require that we be dealing with
+            // strings, so check for that early.
+            if (!isset(HTMLPurifier_VarParser::$stringTypes[$d->type])) {
+                $this->error('type', 'must be a string type when used with allowed or value aliases');
+            }
+        }
+        
+        $this->validateDirectiveAllowed($d);
+        $this->validateDirectiveValueAliases($d);
+        
+        array_pop($this->context);
+    }
+    
+    public function validateDirectiveAllowed($d) {
+        if (is_null($d->allowed)) return;
+        $this->with($d, 'allowed')
+            ->assertNotEmpty()
+            ->assertIsLookup(); // handled by InterchangeBuilder
+        $this->context[] = 'allowed';
+        foreach ($d->allowed as $val => $x) {
+            if (!is_string($val)) $this->error("value $val", 'must be a string');
+        }
+        array_pop($this->context);
+    }
+    
+    public function validateDirectiveValueAliases($d) {
+        if (is_null($d->valueAliases)) return;
+        $this->with($d, 'valueAliases')
+            ->assertIsArray(); // handled by InterchangeBuilder
+        $this->context[] = 'valueAliases';
+        foreach ($d->valueAliases as $alias => $real) {
+            if (!is_string($alias)) $this->error("alias $alias", 'must be a string');
+            if (!is_string($real))  $this->error("alias target $real from alias '$alias'",  'must be a string');
+            if ($alias === $real) {
+                $this->error("alias '$alias'", "must not be an alias to itself");
+            }
+        }
+        if (!is_null($d->allowed)) {
+            foreach ($d->valueAliases as $alias => $real) {
+                if (isset($d->allowed[$alias])) {
+                    $this->error("alias '$alias'", 'must not be an allowed value');
+                } elseif (!isset($d->allowed[$real])) {
+                    $this->error("alias '$alias'", 'must be an alias to an allowed value');
+                }
+            }
+        }
         array_pop($this->context);
     }
     
diff --git a/library/HTMLPurifier/ConfigSchema/ValidatorAtom.php b/library/HTMLPurifier/ConfigSchema/ValidatorAtom.php
index ac8d3e5d..2bb99676 100644
--- a/library/HTMLPurifier/ConfigSchema/ValidatorAtom.php
+++ b/library/HTMLPurifier/ConfigSchema/ValidatorAtom.php
@@ -23,6 +23,16 @@ class HTMLPurifier_ConfigSchema_ValidatorAtom
         return $this;
     }
     
+    public function assertIsBool() {
+        if (!is_bool($this->contents)) $this->error('must be a boolean');
+        return $this;
+    }
+    
+    public function assertIsArray() {
+        if (!is_array($this->contents)) $this->error('must be an array');
+        return $this;
+    }
+    
     public function assertNotNull() {
         if ($this->contents === null) $this->error('must not be null');
         return $this;
@@ -39,6 +49,14 @@ class HTMLPurifier_ConfigSchema_ValidatorAtom
         return $this;
     }
     
+    public function assertIsLookup() {
+        $this->assertIsArray();
+        foreach ($this->contents as $v) {
+            if ($v !== true) $this->error('must be a lookup array');
+        }
+        return $this;
+    }
+    
     protected function error($msg) {
         throw new HTMLPurifier_ConfigSchema_Exception(ucfirst($this->member) . ' in ' . $this->context . ' ' . $msg);
     }
diff --git a/library/HTMLPurifier/VarParser.php b/library/HTMLPurifier/VarParser.php
index 479d18ad..418622be 100644
--- a/library/HTMLPurifier/VarParser.php
+++ b/library/HTMLPurifier/VarParser.php
@@ -24,6 +24,17 @@ class HTMLPurifier_VarParser
         'mixed'     => true
     );
     
+    /**
+     * Lookup table of types that are string, and can have aliases or
+     * allowed value lists.
+     */
+    static public $stringTypes = array(
+        'string'    => true,
+        'istring'   => true,
+        'text'      => true,
+        'itext'     => true,
+    );
+    
     /**
      * Validate a variable according to type. Throws
      * HTMLPurifier_VarParserException if invalid.
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/directive/allowedIsString.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/directive/allowedIsString.vtest
new file mode 100644
index 00000000..09e175cf
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/directive/allowedIsString.vtest
@@ -0,0 +1,10 @@
+ERROR: Value 3 in allowed in directive 'Ns.Dir' must be a string
+----
+Ns
+DESCRIPTION: Generic namespace.
+----
+ID: Ns.Dir
+TYPE: string
+DESCRIPTION: Description
+DEFAULT: 'asdf'
+ALLOWED: 'asdf', 3
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/directive/allowedNotEmpty.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/directive/allowedNotEmpty.vtest
new file mode 100644
index 00000000..bd27e9f1
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/directive/allowedNotEmpty.vtest
@@ -0,0 +1,10 @@
+ERROR: Allowed in directive 'Ns.Dir' must not be empty
+----
+Ns
+DESCRIPTION: Generic namespace.
+----
+ID: Ns.Dir
+TYPE: string
+DESCRIPTION: Description
+DEFAULT: 'asdf'
+ALLOWED: 
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/directive/typeWithAllowedIsStringType.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/directive/typeWithAllowedIsStringType.vtest
new file mode 100644
index 00000000..6ec1ecd8
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/directive/typeWithAllowedIsStringType.vtest
@@ -0,0 +1,10 @@
+ERROR: Type in directive 'Ns.Dir' must be a string type when used with allowed or value aliases
+----
+Ns
+DESCRIPTION: Namespace
+----
+Ns.Dir
+DESCRIPTION: Directive
+TYPE: int
+DEFAULT: 3
+ALLOWED: 1, 2, 3
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/directive/typeWithValueAliasesIsStringType.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/directive/typeWithValueAliasesIsStringType.vtest
new file mode 100644
index 00000000..5569c217
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/directive/typeWithValueAliasesIsStringType.vtest
@@ -0,0 +1,10 @@
+ERROR: Type in directive 'Ns.Dir' must be a string type when used with allowed or value aliases
+----
+Ns
+DESCRIPTION: Namespace
+----
+Ns.Dir
+DESCRIPTION: Directive
+TYPE: int
+DEFAULT: 3
+VALUE-ALIASES: 2 => 3
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/directive/valueAliasesAliasIsString.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/directive/valueAliasesAliasIsString.vtest
new file mode 100644
index 00000000..06eb6ebe
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/directive/valueAliasesAliasIsString.vtest
@@ -0,0 +1,10 @@
+ERROR: Alias 3 in valueAliases in directive 'Ns.Dir' must be a string
+----
+Ns
+DESCRIPTION: Namespace
+----
+Ns.Dir
+DESCRIPTION: Directive
+TYPE: string
+DEFAULT: 'a'
+VALUE-ALIASES: 3 => 'a'
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/directive/valueAliasesAliasNotAllowed.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/directive/valueAliasesAliasNotAllowed.vtest
new file mode 100644
index 00000000..afb06bd3
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/directive/valueAliasesAliasNotAllowed.vtest
@@ -0,0 +1,11 @@
+ERROR: Alias 'b' in valueAliases in directive 'Ns.Dir' must not be an allowed value
+----
+Ns
+DESCRIPTION: Namespace
+----
+Ns.Dir
+DESCRIPTION: Directive
+TYPE: string
+DEFAULT: 'a'
+ALLOWED: 'a', 'b', 'c'
+VALUE-ALIASES: 'b' => 'c'
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/directive/valueAliasesNotAliasSelf.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/directive/valueAliasesNotAliasSelf.vtest
new file mode 100644
index 00000000..354e3317
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/directive/valueAliasesNotAliasSelf.vtest
@@ -0,0 +1,10 @@
+ERROR: Alias 'bar' in valueAliases in directive 'Ns.Dir' must not be an alias to itself
+----
+Ns
+DESCRIPTION: Namespace
+----
+Ns.Dir
+DESCRIPTION: Directive
+TYPE: string
+DEFAULT: 'foo'
+VALUE-ALIASES: 'bar' => 'bar'
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/directive/valueAliasesRealAllowed.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/directive/valueAliasesRealAllowed.vtest
new file mode 100644
index 00000000..26c1b1de
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/directive/valueAliasesRealAllowed.vtest
@@ -0,0 +1,11 @@
+ERROR: Alias 'c' in valueAliases in directive 'Ns.Dir' must be an alias to an allowed value
+----
+Ns
+DESCRIPTION: Namespace
+----
+Ns.Dir
+DESCRIPTION: Directive
+TYPE: string
+DEFAULT: 'a'
+ALLOWED: 'a', 'b'
+VALUE-ALIASES: 'c' => 'd'
diff --git a/tests/HTMLPurifier/ConfigSchema/Validator/directive/valueAliasesRealIsString.vtest b/tests/HTMLPurifier/ConfigSchema/Validator/directive/valueAliasesRealIsString.vtest
new file mode 100644
index 00000000..e06fb294
--- /dev/null
+++ b/tests/HTMLPurifier/ConfigSchema/Validator/directive/valueAliasesRealIsString.vtest
@@ -0,0 +1,10 @@
+ERROR: Alias target 3 from alias 'b' in valueAliases in directive 'Ns.Dir' must be a string
+----
+Ns
+DESCRIPTION: Namespace
+----
+Ns.Dir
+DESCRIPTION: Directive
+TYPE: string
+DEFAULT: 'a'
+VALUE-ALIASES: 'b' => 3
diff --git a/tests/HTMLPurifier/ConfigSchema/ValidatorAtomTest.php b/tests/HTMLPurifier/ConfigSchema/ValidatorAtomTest.php
index fe6cc262..018d3ba0 100644
--- a/tests/HTMLPurifier/ConfigSchema/ValidatorAtomTest.php
+++ b/tests/HTMLPurifier/ConfigSchema/ValidatorAtomTest.php
@@ -55,4 +55,36 @@ class HTMLPurifier_ConfigSchema_ValidatorAtomTest extends UnitTestCase
         $this->makeAtom('')->assertNotEmpty();
     }
     
+    public function testAssertIsBool() {
+        $this->makeAtom(false)->assertIsBool();
+    }
+    
+    public function testAssertIsBoolFail() {
+        $this->expectValidationException("Property in context must be a boolean");
+        $this->makeAtom('0')->assertIsBool();
+    }
+    
+    public function testAssertIsArray() {
+        $this->makeAtom(array())->assertIsArray();
+    }
+    
+    public function testAssertIsArrayFail() {
+        $this->expectValidationException("Property in context must be an array");
+        $this->makeAtom('asdf')->assertIsArray();
+    }
+    
+    
+    public function testAssertIsLookup() {
+        $this->makeAtom(array('foo' => true))->assertIsLookup();
+    }
+    
+    public function testAssertIsLookupFail() {
+        $this->expectValidationException("Property in context must be a lookup array");
+        $this->makeAtom(array('foo' => 4))->assertIsLookup();
+    }
+    
+    public function testAssertIsLookupFailIsArray() {
+        $this->expectValidationException("Property in context must be an array");
+        $this->makeAtom('asdf')->assertIsLookup();
+    }
 }
diff --git a/tests/HTMLPurifier/ConfigSchema/ValidatorTest.php b/tests/HTMLPurifier/ConfigSchema/ValidatorTest.php
index f5fa49e0..663102b9 100644
--- a/tests/HTMLPurifier/ConfigSchema/ValidatorTest.php
+++ b/tests/HTMLPurifier/ConfigSchema/ValidatorTest.php
@@ -72,6 +72,42 @@ class HTMLPurifier_ConfigSchema_ValidatorTest extends UnitTestCase
         $this->validator->validate($this->interchange);
     }
     
+    public function testDirectiveTypeAllowsNullIsBool() {
+        $this->makeNamespace('Ns');
+        $d = $this->makeDirective('Ns', 'Dir');
+        $d->default = 0;
+        $d->type = 'int';
+        $d->description = 'Description';
+        $d->typeAllowsNull = 'yes';
+        
+        $this->expectValidationException("TypeAllowsNull in directive 'Ns.Dir' must be a boolean");
+        $this->validator->validate($this->interchange);
+    }
+    
+    public function testDirectiveValueAliasesIsArray() {
+        $this->makeNamespace('Ns');
+        $d = $this->makeDirective('Ns', 'Dir');
+        $d->default = 'a';
+        $d->type = 'string';
+        $d->description = 'Description';
+        $d->valueAliases = 2;
+        
+        $this->expectValidationException("ValueAliases in directive 'Ns.Dir' must be an array");
+        $this->validator->validate($this->interchange);
+    }
+    
+    public function testDirectiveAllowedIsLookup() {
+        $this->makeNamespace('Ns');
+        $d = $this->makeDirective('Ns', 'Dir');
+        $d->default = 'foo';
+        $d->type = 'string';
+        $d->description = 'Description';
+        $d->allowed = array('foo' => 1);
+        
+        $this->expectValidationException("Allowed in directive 'Ns.Dir' must be a lookup array");
+        $this->validator->validate($this->interchange);
+    }
+    
     // helper functions
     
     protected function makeNamespace($n) {