diff --git a/htdocs/core/lib/functions.lib.php b/htdocs/core/lib/functions.lib.php
index 54320ddf928..5b05a9a2071 100644
--- a/htdocs/core/lib/functions.lib.php
+++ b/htdocs/core/lib/functions.lib.php
@@ -9148,7 +9148,15 @@ function natural_search($fields, $value, $mode = 0, $nofirstand = 0)
 					if (preg_match('/\.(id|rowid)$/', $field)) {	// Special case for rowid that is sometimes a ref so used as a search field
 						$newres .= $field." = ".(is_numeric(trim($tmpcrit)) ? ((float) trim($tmpcrit)) : '0');
 					} else {
-						$newres .= $field." LIKE '";
+						$tmpcrit = trim($tmpcrit);
+						$tmpcrit2 = $tmpcrit;
+						$tmpbefore = '%';
+						$tmpafter = '%';						
+						if(preg_match('/^!/', $tmpcrit)) {
+							$newres .= $field." NOT LIKE '"; // ! as exclude character
+							$tmpcrit2 = preg_replace('/^!/', '', $tmpcrit2);
+						}
+						else $newres .= $field." LIKE '";
 
 						$tmpcrit = trim($tmpcrit);
 						$tmpcrit2 = $tmpcrit;