diff --git a/.github/workflows/release-pr.yml b/.github/workflows/release-pr.yml
index cb1e8c1ef..46e18c450 100644
--- a/.github/workflows/release-pr.yml
+++ b/.github/workflows/release-pr.yml
@@ -47,7 +47,7 @@ jobs:
           sentry-cli dif upload --project ghostty --wait dsym.zip
 
   build-macos:
-    runs-on: namespace-profile-ghostty-macos-sequoia-edge
+    runs-on: namespace-profile-ghostty-macos-tahoe
     timeout-minutes: 90
     steps:
       - name: Checkout code
@@ -57,9 +57,9 @@ jobs:
           fetch-depth: 0
 
       # Install Nix and use that to run our tests so our environment matches exactly.
-      - uses: cachix/install-nix-action@fc6e360bedc9ee72d75e701397f0bb30dce77568 # v31.5.2
+      - uses: DeterminateSystems/nix-installer-action@main
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
+          determinate: true
       - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         with:
           name: ghostty
@@ -202,7 +202,7 @@ jobs:
           destination-dir: ./
 
   build-macos-debug:
-    runs-on: namespace-profile-ghostty-macos-sequoia-edge
+    runs-on: namespace-profile-ghostty-macos-tahoe
     timeout-minutes: 90
     steps:
       - name: Checkout code
@@ -212,9 +212,9 @@ jobs:
           fetch-depth: 0
 
       # Install Nix and use that to run our tests so our environment matches exactly.
-      - uses: cachix/install-nix-action@fc6e360bedc9ee72d75e701397f0bb30dce77568 # v31.5.2
+      - uses: DeterminateSystems/nix-installer-action@main
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
+          determinate: true
       - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         with:
           name: ghostty
diff --git a/.github/workflows/release-tag.yml b/.github/workflows/release-tag.yml
index bbd013f4e..38eef0b92 100644
--- a/.github/workflows/release-tag.yml
+++ b/.github/workflows/release-tag.yml
@@ -120,7 +120,7 @@ jobs:
 
   build-macos:
     needs: [setup]
-    runs-on: namespace-profile-ghostty-macos-sequoia-edge
+    runs-on: namespace-profile-ghostty-macos-tahoe
     timeout-minutes: 90
     env:
       GHOSTTY_VERSION: ${{ needs.setup.outputs.version }}
@@ -130,9 +130,9 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
-      - uses: cachix/install-nix-action@fc6e360bedc9ee72d75e701397f0bb30dce77568 # v31.5.2
+      - uses: DeterminateSystems/nix-installer-action@main
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
+          determinate: true
       - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         with:
           name: ghostty
@@ -294,7 +294,7 @@ jobs:
 
   appcast:
     needs: [setup, build-macos]
-    runs-on: namespace-profile-ghostty-macos-sequoia-edge
+    runs-on: namespace-profile-ghostty-macos-tahoe
     env:
       GHOSTTY_VERSION: ${{ needs.setup.outputs.version }}
       GHOSTTY_BUILD: ${{ needs.setup.outputs.build }}
diff --git a/.github/workflows/release-tip.yml b/.github/workflows/release-tip.yml
index 791482518..763acf6fa 100644
--- a/.github/workflows/release-tip.yml
+++ b/.github/workflows/release-tip.yml
@@ -154,7 +154,7 @@ jobs:
         )
       }}
 
-    runs-on: namespace-profile-ghostty-macos-sequoia-edge
+    runs-on: namespace-profile-ghostty-macos-tahoe
     timeout-minutes: 90
     steps:
       - name: Checkout code
@@ -163,10 +163,10 @@ jobs:
           # Important so that build number generation works
           fetch-depth: 0
 
-      # Install Nix and use that to run our tests so our environment matches exactly.
-      - uses: cachix/install-nix-action@fc6e360bedc9ee72d75e701397f0bb30dce77568 # v31.5.2
+      # TODO(tahoe): https://github.com/NixOS/nix/issues/13342
+      - uses: DeterminateSystems/nix-installer-action@main
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
+          determinate: true
       - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         with:
           name: ghostty
@@ -374,7 +374,7 @@ jobs:
         )
       }}
 
-    runs-on: namespace-profile-ghostty-macos-sequoia-edge
+    runs-on: namespace-profile-ghostty-macos-tahoe
     timeout-minutes: 90
     steps:
       - name: Checkout code
@@ -383,10 +383,10 @@ jobs:
           # Important so that build number generation works
           fetch-depth: 0
 
-      # Install Nix and use that to run our tests so our environment matches exactly.
-      - uses: cachix/install-nix-action@fc6e360bedc9ee72d75e701397f0bb30dce77568 # v31.5.2
+      # TODO(tahoe): https://github.com/NixOS/nix/issues/13342
+      - uses: DeterminateSystems/nix-installer-action@main
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
+          determinate: true
       - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         with:
           name: ghostty
@@ -554,7 +554,7 @@ jobs:
         )
       }}
 
-    runs-on: namespace-profile-ghostty-macos-sequoia-edge
+    runs-on: namespace-profile-ghostty-macos-tahoe
     timeout-minutes: 90
     steps:
       - name: Checkout code
@@ -563,10 +563,10 @@ jobs:
           # Important so that build number generation works
           fetch-depth: 0
 
-      # Install Nix and use that to run our tests so our environment matches exactly.
-      - uses: cachix/install-nix-action@fc6e360bedc9ee72d75e701397f0bb30dce77568 # v31.5.2
+      # TODO(tahoe): https://github.com/NixOS/nix/issues/13342
+      - uses: DeterminateSystems/nix-installer-action@main
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
+          determinate: true
       - uses: cachix/cachix-action@0fc020193b5a1fa3ac4575aa3a7d3aa6a35435ad # v16
         with:
           name: ghostty