diff --git a/addons/web/static/src/js/search.js b/addons/web/static/src/js/search.js
index 504510ef133..8de2562a798 100644
--- a/addons/web/static/src/js/search.js
+++ b/addons/web/static/src/js/search.js
@@ -1475,7 +1475,17 @@ instance.web.search.ManyToOneField = instance.web.search.CharField.extend({
     facet_for: function (value) {
         var self = this;
         if (value instanceof Array) {
-            return $.when(facet_from(this, value));
+            if (value.length === 2 && _.isString(value[1])) {
+                return $.when(facet_from(this, value));
+            }
+            if (value.length > 1) {
+                // more than one search_default m2o id? Should we OR them?
+                throw new Error(
+                    _("M2O search fields do not currently handle multiple default values"));
+            }
+            // there are many cases of {search_default_$m2ofield: [id]}, need
+            // to handle this as if it were a single value.
+            value = value[0];
         }
         return this.model.call('name_get', [value], {}).pipe(function (names) {
             if (_(names).isEmpty()) { return null; }