diff --git a/harness/estate/drive.js b/harness/estate/drive.cjs
similarity index 100%
rename from harness/estate/drive.js
rename to harness/estate/drive.cjs
diff --git a/harness/estate/fakehs.js b/harness/estate/fakehs.cjs
similarity index 100%
rename from harness/estate/fakehs.js
rename to harness/estate/fakehs.cjs
diff --git a/harness/estate/run.sh b/harness/estate/run.sh
index 085b17dc..b37d3524 100644
--- a/harness/estate/run.sh
+++ b/harness/estate/run.sh
@@ -7,9 +7,9 @@ npm ci --no-audit --no-fund --ignore-scripts >/out/npmci.log 2>&1
 npm run build > /out/build.log 2>&1; echo BUILD_RC=$? >> /out/build.log
 printf '{"defaultHomeserver":0,"homeserverList":["127.0.0.1:8080"],"allowCustomHomeservers":true,"featuredCommunities":{"spaces":["#gamecult:test"],"rooms":[],"servers":["test"]},"hashRouter":{"enabled":true,"basename":"/"}}' > dist/config.json
 mkdir -p /tmp/pw && cd /tmp/pw && npm init -y >/dev/null && npm i --no-audit --no-fund playwright@1.48.2 >/out/pw.log 2>&1
-cp /src/harness/estate/drive.js /tmp/pw/
-HSLOG=/out/hslog.txt node /src/harness/estate/fakehs.js /src/dist > /out/hs.out 2>&1 &
+cp /src/harness/estate/drive.cjs /tmp/pw/
+HSLOG=/out/hslog.txt node /src/harness/estate/fakehs.cjs /src/dist > /out/hs.out 2>&1 &
 HS=$!
 sleep 2
-node /tmp/pw/drive.js; echo DRIVE_RC=$?
+node /tmp/pw/drive.cjs; echo DRIVE_RC=$?
 kill $HS