Index: src/org/openstreetmap/josm/gui/dialogs/properties/TagEditHelper.java
===================================================================
--- src/org/openstreetmap/josm/gui/dialogs/properties/TagEditHelper.java	(revision 14786)
+++ src/org/openstreetmap/josm/gui/dialogs/properties/TagEditHelper.java	(working copy)
@@ -519,7 +519,10 @@
                 return;
             if (key.equals(newkey) || value == null) {
                 UndoRedoHandler.getInstance().add(new ChangePropertyCommand(sel, newkey, value));
-                AutoCompletionManager.rememberUserInput(newkey, value, true);
+                if (value != null) {
+                    AutoCompletionManager.rememberUserInput(newkey, value, true);
+                    recentTags.add(new Tag(key, value));
+                }
             } else {
                 for (OsmPrimitive osm: sel) {
                     if (osm.get(newkey) != null) {