diff --git a/tools/js-runtimes/Cargo.toml b/tools/js-runtimes/Cargo.toml
index 451dcb990..9586888c4 100644
--- a/tools/js-runtimes/Cargo.toml
+++ b/tools/js-runtimes/Cargo.toml
@@ -20,3 +20,11 @@ path = "src/main.rs"
 # I-JSON (RFC 7493) + JCS (RFC 8785), in-process (owner ruling D306).
 # Pinned by commit: ijson-jcs has no releases yet.
 ijson-jcs = { git = "https://github.com/hyperpolymath/ijson-jcs", rev = "3a9a4ee326a968a32b2f152b4faec243a2d00765" }
+
+# Its own workspace root, on purpose. The governance and js-runtimes
+# reusables check this crate out at .standards-js/ INSIDE the caller's
+# checkout and `cargo install --path` it from there. In a caller whose root
+# Cargo.toml is a workspace, cargo would otherwise take this crate for an
+# undeclared member and refuse to build it ("current package believes it's
+# in a workspace when it's not"). Hit by hyperpolymath/hypatia#929.
+[workspace]