diff --git a/library/ajax/edit_user_profile.php b/library/ajax/edit_user_profile.php
index 65aab1d2..e2af0e69 100644
--- a/library/ajax/edit_user_profile.php
+++ b/library/ajax/edit_user_profile.php
@@ -128,6 +128,11 @@ switch ($field)
 		$table = BB_BT_USERS;
 		$value = (float) str_replace(',', '.', $this->request['value']);
 
+		if ($value < 0.0)
+		{
+			$this->ajax_die($lang['WRONG_INPUT']);
+		}
+
 		foreach (array('KB'=>1,'MB'=>2,'GB'=>3,'TB'=>4,'PB'=>5,'EB'=>6,'ZB'=>7,'YB'=>8) as $s => $m)
 		{
 			if (stripos($this->request['value'], $s) !== false)