diff --git a/include/lib/html_input.class.php b/include/lib/html_input.class.php
index a90af4d41..ba6d1c4e8 100755
--- a/include/lib/html_input.class.php
+++ b/include/lib/html_input.class.php
@@ -336,7 +336,7 @@ class HtmlInput
         }
         $js=sprintf('onclick="view_history_card(\'%s\',\'%s\',\'%s\')"', $f_id,
                 dossier::id(),$p_exercice);
-        $view_history=HtmlInput::button("hcb"+$e, $p_mesg, $js);
+        $view_history=HtmlInput::button("hcb".$e, $p_mesg, $js);
         return $view_history;
     }