diff --git a/NEWS b/NEWS
index 4ef5ab25..57ce8ec8 100644
--- a/NEWS
+++ b/NEWS
@@ -20,6 +20,7 @@ NEWS ( CHANGELOG and HISTORY )                                     HTMLPurifier
 ! Added enduser-youtube.html, explains how to embed YouTube videos. See
   also corresponding smoketest preserveYouTube.php.
 ! Added purifyArray(), which takes a list of HTML and purifies it all
+- Fixed fatal error thrown by upper-cased language attributes
 - printDefinition.php: added labels, added better clarification
 . HTMLPurifier_Config::create() added, takes mixed variable and converts into
   a HTMLPurifier_Config object.
diff --git a/library/HTMLPurifier/AttrDef/Lang.php b/library/HTMLPurifier/AttrDef/Lang.php
index 58809c2b..67183747 100644
--- a/library/HTMLPurifier/AttrDef/Lang.php
+++ b/library/HTMLPurifier/AttrDef/Lang.php
@@ -49,7 +49,7 @@ class HTMLPurifier_AttrDef_Lang extends HTMLPurifier_AttrDef
         if ($length == 0 || $length == 1 || $length > 8 || !ctype_alnum($subtags[1])) {
             return $new_string;
         }
-        if (!ctype_lower($subtags[1])) $subtags[1] = strotolower($subtags[1]);
+        if (!ctype_lower($subtags[1])) $subtags[1] = strtolower($subtags[1]);
         
         $new_string .= '-' . $subtags[1];
         if ($num_subtags == 2) return $new_string;
@@ -61,7 +61,7 @@ class HTMLPurifier_AttrDef_Lang extends HTMLPurifier_AttrDef
                 return $new_string;
             }
             if (!ctype_lower($subtags[$i])) {
-                $subtags[$i] = strotolower($subtags[$i]);
+                $subtags[$i] = strtolower($subtags[$i]);
             }
             $new_string .= '-' . $subtags[$i];
         }
diff --git a/tests/HTMLPurifier/AttrDef/LangTest.php b/tests/HTMLPurifier/AttrDef/LangTest.php
index 216a7a88..7a0e4308 100644
--- a/tests/HTMLPurifier/AttrDef/LangTest.php
+++ b/tests/HTMLPurifier/AttrDef/LangTest.php
@@ -17,6 +17,9 @@ class HTMLPurifier_AttrDef_LangTest extends HTMLPurifier_AttrDefHarness
         $this->assertDef(' en ', 'en'); // trim
         $this->assertDef('EN', 'en'); // case insensitivity
         
+        // (thanks Eugen Pankratz for noticing the typos!)
+        $this->assertDef('En-Us-Edison', 'en-us-edison'); // complex ci
+        
         $this->assertDef('fr en', false); // multiple languages
         $this->assertDef('%', false); // bad character
         
@@ -26,7 +29,7 @@ class HTMLPurifier_AttrDef_LangTest extends HTMLPurifier_AttrDefHarness
         // primary subtag rules
             // I'm somewhat hesitant to allow x and i as primary language codes,
             // because they usually are never used in real life. However,
-            // theoretically speaking, having them alone is permissble, so
+            // theoretically speaking, having them alone is permissable, so
             // I'll be lenient. No XML parser is going to complain anyway.
         $this->assertDef('x');
         $this->assertDef('i');