diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 70d0e7f..2142247 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -14,7 +14,7 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Install Nix
-        uses: DeterminateSystems/nix-installer-action@v6
+        uses: DeterminateSystems/nix-installer-action@v22
 
       # Delegate to `just ci` so the gate has a single definition. Spelling the
       # steps out here is what let CI drift: it used to run `cargo fmt --all`
@@ -51,7 +51,7 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Install Nix
-        uses: DeterminateSystems/nix-installer-action@v6
+        uses: DeterminateSystems/nix-installer-action@v22
 
       # The installer enables flakes by default; pin the behaviour so a change
       # of default cannot silently break this job.