Index: wp-includes/class-snoopy.php
===================================================================
--- wp-includes/class-snoopy.php	(revision 12686)
+++ wp-includes/class-snoopy.php	(working copy)
@@ -1,5 +1,5 @@
 <?php
-if ( !in_array('Snoopy', get_declared_classes() ) ) :
+if ( !class_exists( 'Snoopy' ) ) :
 /*************************************************
 
 Snoopy - the PHP net client
Index: wp-includes/class-simplepie.php
===================================================================
--- wp-includes/class-simplepie.php	(revision 12686)
+++ wp-includes/class-simplepie.php	(working copy)
@@ -1,4 +1,5 @@
 <?php
+if ( !class_exists( 'SimplePie' ) ) :
 /**
  * SimplePie
  *
@@ -14997,5 +14998,5 @@
 		}
 	}
 }
-
+endif;
 ?>
Index: wp-includes/class-json.php
===================================================================
--- wp-includes/class-json.php	(revision 12686)
+++ wp-includes/class-json.php	(working copy)
@@ -1,4 +1,5 @@
 <?php
+if ( !class_exists( 'Services_JSON' ) ) :
 /* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */
 /**
  * Converts to and from JSON format.
@@ -858,3 +859,5 @@
 	}
 
 }
+endif;
+?>