Index: /trunk/src/org/openstreetmap/josm/actions/CreateMultipolygonAction.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/actions/CreateMultipolygonAction.java	(revision 12187)
+++ /trunk/src/org/openstreetmap/josm/actions/CreateMultipolygonAction.java	(revision 12188)
@@ -32,4 +32,5 @@
 import org.openstreetmap.josm.data.osm.MultipolygonBuilder.JoinedPolygon;
 import org.openstreetmap.josm.data.osm.OsmPrimitive;
+import org.openstreetmap.josm.data.osm.OsmUtils;
 import org.openstreetmap.josm.data.osm.Relation;
 import org.openstreetmap.josm.data.osm.RelationMember;
@@ -401,5 +402,5 @@
             values.remove("natural");
 
-        values.put("area", "yes");
+        values.put("area", OsmUtils.TRUE_VALUE);
 
         List<Command> commands = new ArrayList<>();
Index: /trunk/src/org/openstreetmap/josm/data/osm/OsmPrimitive.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/data/osm/OsmPrimitive.java	(revision 12187)
+++ /trunk/src/org/openstreetmap/josm/data/osm/OsmPrimitive.java	(revision 12188)
@@ -1352,5 +1352,5 @@
     public final boolean hasAreaTags() {
         return hasKey("landuse", "amenity", "building", "building:part")
-                || hasTag("area", "yes")
+                || hasTag("area", OsmUtils.TRUE_VALUE)
                 || hasTag("waterway", "riverbank")
                 || hasTagDifferent("leisure", "picnic_table", "slipway", "firepit")