Index: src/wp-admin/js/revisions.js
===================================================================
--- src/wp-admin/js/revisions.js	(revision 30824)
+++ src/wp-admin/js/revisions.js	(working copy)
@@ -405,7 +405,7 @@
 			this.set( {
 				to : this.revisions.get( state.to ),
 				from : this.revisions.get( state.from ),
-				compareTwoMode : this.revisions.get( state.compareTwoMode )
+				compareTwoMode : state.compareTwoMode
 			} );
 
 			// Start the router if browser supports History API