diff --git a/scripts/fetch-develop.deps.sh b/scripts/fetch-develop.deps.sh
index 0625cec897..421656ed94 100755
--- a/scripts/fetch-develop.deps.sh
+++ b/scripts/fetch-develop.deps.sh
@@ -76,7 +76,7 @@ dodep matrix-org matrix-js-sdk
 
 pushd matrix-js-sdk
 yarn link
-yarn install
+yarn install --pure-lockfile
 popd
 
 yarn link matrix-js-sdk
@@ -90,7 +90,7 @@ dodep matrix-org matrix-react-sdk
 pushd matrix-react-sdk
 yarn link
 yarn link matrix-js-sdk
-yarn install
+yarn install --pure-lockfile
 yarn reskindex
 popd