diff --git a/htdocs/core/lib/functions.lib.php b/htdocs/core/lib/functions.lib.php
index 29b47a624b3..4b7e6bf4015 100644
--- a/htdocs/core/lib/functions.lib.php
+++ b/htdocs/core/lib/functions.lib.php
@@ -635,7 +635,7 @@ function GETPOST($paramname, $check = 'alphanohtml', $method = 0, $filter = null
 	}
 
 	if (empty($method) || $method == 3 || $method == 4) {
-		$relativepathstring = $_SERVER["PHP_SELF"];
+		$relativepathstring = (empty($_SERVER["PHP_SELF"]) ? '' : $_SERVER["PHP_SELF"]);
 		// Clean $relativepathstring
 		if (constant('DOL_URL_ROOT')) {
 			$relativepathstring = preg_replace('/^'.preg_quote(constant('DOL_URL_ROOT'), '/').'/', '', $relativepathstring);