diff --git a/src/librustdoc/json/mod.rs b/src/librustdoc/json/mod.rs
index df7ab9b7361a..e96ceb32f2e9 100644
--- a/src/librustdoc/json/mod.rs
+++ b/src/librustdoc/json/mod.rs
@@ -236,7 +236,7 @@ impl<'tcx> FormatRenderer<'tcx> for JsonRenderer<'tcx> {
                     )
                 })
                 .collect(),
-            format_version: 1,
+            format_version: 2,
         };
         let mut p = self.out_path.clone();
         p.push(output.index.get(&output.root).unwrap().name.clone().unwrap());