diff --git a/ZAbsences.py b/ZAbsences.py
index e9cd2f378d..52a68c6a24 100644
--- a/ZAbsences.py
+++ b/ZAbsences.py
@@ -795,7 +795,7 @@ class ZAbsences(
             <input type="hidden" name="moduleimpl_id" id="moduleimpl_id_o" value="%s"/>
             Groupes: %s
             </form>
-            <form>              
+            <form id="abs_form">
             """
             % (
                 gr_tit,
@@ -983,7 +983,7 @@ class ZAbsences(
               les <span class="fontred">%s</span></h2>
               <p>
               <a href="%s">%s</a>
-              <form action="doSignaleAbsenceGrSemestre" method="post">              
+              <form id="abs_form" action="doSignaleAbsenceGrSemestre" method="post">
               """
             % (gr_tit, sem["titre_num"], dayname, url_link_semaines, msg),
         ]
diff --git a/static/js/abs_ajax.js b/static/js/abs_ajax.js
index a6f99fe8b6..bea7c45616 100644
--- a/static/js/abs_ajax.js
+++ b/static/js/abs_ajax.js
@@ -30,10 +30,9 @@ function ajaxFunction(mod, etudid, dat) {
 	}
 	ajaxRequest.open("POST", "doSignaleAbsenceGrSemestre", true);
 	ajaxRequest.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
-	oForm = document.forms[1];
-	oSelectOne = oForm.elements["moduleimpl_id"];
-	index = oSelectOne.selectedIndex;
-	modul_id = oSelectOne.options[index].value;
+	var oSelectOne = $("#abs_form")[0].elements["moduleimpl_id"];
+	var index = oSelectOne.selectedIndex;
+	var modul_id = oSelectOne.options[index].value;
 	if (mod == 'add') {
 		ajaxRequest.send("reply=0&moduleimpl_id=" + modul_id + "&abslist:list=" + etudid + ":" + dat);
 	}