diff --git a/runtimes/rust b/runtimes/rust
index e9c3cc9..09cd2df 100644
--- a/runtimes/rust
+++ b/runtimes/rust
@@ -34,6 +34,11 @@
              gerrithost="https://fuchsia-review.googlesource.com"
              githooks="manifest/git-hooks"
              historydepth="1"/>
+    <project name="third_party/serde_json5"
+             path="third_party/rust-mirrors/serde_json5"
+             remote="https://fuchsia.googlesource.com/third_party/serde_json5"
+             gerrithost="https://fuchsia-review.googlesource.com"
+             githooks="manifest/git-hooks"/>
     <project name="third_party/tokio-core"
              path="third_party/rust-mirrors/tokio-core"
              remote="https://fuchsia.googlesource.com/third_party/tokio-core"