diff --git a/navalplanner-webapp/src/main/webapp/orders/_listOrderElementMaterials.zul b/navalplanner-webapp/src/main/webapp/orders/_listOrderElementMaterials.zul
index 3d189cb33..c7a3ea97e 100644
--- a/navalplanner-webapp/src/main/webapp/orders/_listOrderElementMaterials.zul
+++ b/navalplanner-webapp/src/main/webapp/orders/_listOrderElementMaterials.zul
@@ -146,6 +146,7 @@
                                 </hbox>
 
                                 <listbox id="lbFoundMaterials"
+                                    multiple="true"
                                     fixedLayout="true"
                                     model="@{assignedMaterialsController.matchingMaterials}">
                                     <listhead sizable="true">