diff --git a/lib/update-v8/updateCrates.js b/lib/update-v8/updateCrates.js
index de3f6d73..672cb3c3 100644
--- a/lib/update-v8/updateCrates.js
+++ b/lib/update-v8/updateCrates.js
@@ -31,9 +31,16 @@ function enumerateTemporalDependencies() {
   return {
     title: 'Enumerate Temporal dependency tree',
     task: async(ctx) => {
+      // Resolve against the vendored crates rather than crates.io. Chromium patches some
+      // vendored manifests (e.g. relaxing version pins), and the lockfile only resolves
+      // with those patches applied.
       const tree = await forceRunAsync(
         ctx.cargo,
-        ['tree', '-Z', 'bindeps', '--package', 'temporal_capi', '--prefix', 'none'],
+        [
+          'tree', '-Z', 'bindeps', '--package', 'temporal_capi', '--prefix', 'none',
+          '--config', 'source.crates-io.replace-with="vendored-sources"',
+          '--config', 'source.vendored-sources.directory="vendor"'
+        ],
         {
           ignoreFailure: false,
           captureStdout: true,