diff --git a/addons/web/static/src/js/pyeval.js b/addons/web/static/src/js/pyeval.js
index 554c4aa7db0..c1e1264aaf5 100644
--- a/addons/web/static/src/js/pyeval.js
+++ b/addons/web/static/src/js/pyeval.js
@@ -502,12 +502,15 @@ openerp.web.pyeval = function (instance) {
         return py.PY_call(py.PY_getAttr(d, 'strftime'), [args.format]);
     });
 
+    var args = _.map(('year month day hour minute second microsecond '
+                    + 'years months weeks days hours minutes secondes microseconds '
+                    + 'weekday leakdays yearday nlyearday').split(' '), function (arg) {
+        return [arg, null]
+    });
+    args.unshift('*');
     var relativedelta = py.type('relativedelta', null, {
         __init__: function () {
-            this.ops = py.PY_parseArgs(arguments,
-                '* year month day hour minute second microsecond '
-                + 'years months weeks days hours minutes secondes microseconds '
-                + 'weekday leakdays yearday nlyearday');
+            this.ops = py.PY_parseArgs(arguments, args);
         },
         __add__: function (other) {
             if (!py.PY_isInstance(other, datetime.date)) {
diff --git a/addons/web/static/test/evals.js b/addons/web/static/test/evals.js
index 0e1c1351b98..2cc3655a0aa 100644
--- a/addons/web/static/test/evals.js
+++ b/addons/web/static/test/evals.js
@@ -259,6 +259,12 @@ openerp.testing.section('eval.types', {
             py.eval('a + a', ctx);
         }, /^Error: TypeError:/);
     });
+    test('relastivedelta', function (instance) {
+        strictEqual(
+            py.eval("(datetime.date(2012, 2, 15) + relativedelta(days=-1)).strftime('%Y-%m-%d 23:59:59')",
+                    instance.web.pyeval.context()),
+            "2012-02-14 23:59:59");
+    })
 });
 openerp.testing.section('eval.edc', {
     dependencies: ['web.data'],