diff --git a/htdocs/core/lib/functions.lib.php b/htdocs/core/lib/functions.lib.php
index 7c314c08be1..18c0558b465 100644
--- a/htdocs/core/lib/functions.lib.php
+++ b/htdocs/core/lib/functions.lib.php
@@ -561,7 +561,8 @@ function GETPOST($paramname, $check = 'alphanohtml', $method = 0, $filter = null
 
 	// Sanitizing for special parameters. There is no reason to allow the backtopage parameter to contains an external URL.
 	if ($paramname == 'backtopage') {
-		$out = preg_replace(array('!(\\\|/)+!', '/^[a-z]*:/'), '', $out);
+		$out = str_replace('\\', '/', $out);
+		$out = preg_replace(array('/^\/\/+/', '/^[a-z]*:/i'), '', $out);
 	}
 
 	// Code for search criteria persistence.