Index: wp-includes/functions.php
===================================================================
--- wp-includes/functions.php	(revision 12484)
+++ wp-includes/functions.php	(working copy)
@@ -263,7 +263,7 @@
 		case 'b' :
 		case 'i' :
 		case 'd' :
-			if ( preg_match( "/^{$badions[1]}:[0-9.E-]+;\$/", $data ) )
+			if ( preg_match( "/^{$badions[1]}:[0-9.E+-]+;\$/", $data ) )
 				return true;
 			break;
 	}