diff --git a/ci-tools/update-nixpkgs b/ci-tools/update-nixpkgs
index a017c2d1ea5f961eefa7c3c365c480f7d77130f2..77d8e3bf4c6dd88950b622fed14cd2e1add95ae3 100755
--- a/ci-tools/update-nixpkgs
+++ b/ci-tools/update-nixpkgs
@@ -6,6 +6,7 @@
 # we need git to commit and push our changes
 # we need openssh for ssh-agent to authenticate the push
 # we need curl to create the gitlab MR
+# we need python to format the data as json
 
 set -eux -o pipefail
 
@@ -29,30 +30,28 @@ setup_ssh() {
 setup_git() {
     git config --global user.email "update-bot@private.storage"
     git config --global user.name "Update Bot"
-    git remote remove origin || true
-    git remote add origin "gitlab@${HOST}:PrivateStorage/PrivateStorageio.git"
 }
 
 setup_ssh
 setup_git
 
-export TARGET_BRANCH="nixpkgs-upgrade-$(date +%Y-%m-%d)"
+export SOURCE_BRANCH="nixpkgs-upgrade-$(date +%Y-%m-%d)"
+
+# Avoid messing with the checkout we're running from.
+git clone . working-copy
+cd working-copy
+git branch -D "${SOURCE_BRANCH}" || true
+git checkout -B "${SOURCE_BRANCH}" origin/develop
 
 echo '{}' > morph/grid/local/public-keys/users.nix
 nix-build -A morph -o result-before
 
-git branch -D "${TARGET_BRANCH}" || true
-git checkout -b "${TARGET_BRANCH}"
-
 # Spawn *another* nix-shell that has the *other* update-nixpkgs tool.  Should
 # sort out this mess sooner rather than later...
-nix-shell ./shell.nix --run 'update-nixpkgs'
-
-git fetch origin develop
-git branch -a
+nix-shell ../shell.nix --run 'update-nixpkgs ./nixpkgs.json'
 
 # Show us what we did
-if git diff --exit-code origin/develop...; then
+if git diff --exit-code; then
     echo "No changes."
     exit 0
 fi
@@ -61,13 +60,13 @@ nix-build -A morph -o result-after
 DIFF=$(nix --extra-experimental-features nix-command store diff-closures ./result-before/ ./result-after/)
 
 git commit -am "bump nixpkgs version"
-git push --force origin "${TARGET_BRANCH}:${TARGET_BRANCH}"
+git push --force origin "${SOURCE_BRANCH}:${SOURCE_BRANCH}"
 
 BODY=$(python3 -c '
 import os, sys, json
 print(json.dumps({
     "id": os.environ["CI_PROJECT_ID"],
-    "source_branch": os.environ["TARGET_BRANCH"],
+    "source_branch": os.environ["SOURCE_BRANCH"],
     "target_branch": "develop",
     "remove_source_branch": True,
     "title": "bump nixpkgs version",