tweaked and dropped the strtolower altogether from checking xmlrpcTypes array since it's accessed later without changing the type's casing anyway
diff --git a/system/libraries/Xmlrpc.php b/system/libraries/Xmlrpc.php
index 4b3470c..5460842 100644
--- a/system/libraries/Xmlrpc.php
+++ b/system/libraries/Xmlrpc.php
@@ -231,7 +231,7 @@
 	{
 		if (is_array($value) && isset($value['0']))
 		{
-			if ( ! isset($value['1']) OR (! isset($this->xmlrpcTypes[$value['1']]) && ! isset($this->xmlrpcTypes[strtolower($value['1'])])))
+			if ( ! isset($value['1']) OR (! isset($this->xmlrpcTypes[$value['1']])))
 			{
 				if (is_array($value[0]))
 				{