Index: trunk/data/validator/deprecated.mapcss
===================================================================
--- trunk/data/validator/deprecated.mapcss	(revision 7969)
+++ trunk/data/validator/deprecated.mapcss	(revision 7973)
@@ -372,2 +372,9 @@
   fixChangeKey: "levels => building:levels";
 }
+
+/* see #10691 */
+*[protected_class] {
+  throwWarning: tr("{0} is deprecated", "{0.key}");
+  suggestAlternative: "protect_class";
+  fixChangeKey: "protected_class => protect_class";
+}