diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index de03ad6b..7d8efb32 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -34,7 +34,7 @@ jobs:
       # * https://github.com/actions/cache/blob/main/examples.md#rust---cargo.
       # * https://doc.rust-lang.org/cargo/guide/cargo-home.html#caching-the-cargo-home-in-ci
       # The rest were added by me.
-      - uses: actions/cache@v3
+      - uses: actions/cache@v4
         with:
           path: |
             ~/.cargo/bin/
diff --git a/.github/workflows/update_patches.yml b/.github/workflows/update_patches.yml
index 11cc592b..1a4c4c90 100644
--- a/.github/workflows/update_patches.yml
+++ b/.github/workflows/update_patches.yml
@@ -15,7 +15,7 @@ jobs:
           ssh-key: ${{ secrets.PR_SSH_KEY }}
 
       # smoelius: The next use of `actions/cache` should match what is in ci.yml.
-      - uses: actions/cache@v3
+      - uses: actions/cache@v4
         with:
           path: |
             ~/.cargo/bin/
diff --git a/.github/workflows/update_supply_chain.yml b/.github/workflows/update_supply_chain.yml
index d8f7cf93..83a4c1c0 100644
--- a/.github/workflows/update_supply_chain.yml
+++ b/.github/workflows/update_supply_chain.yml
@@ -15,7 +15,7 @@ jobs:
           ssh-key: ${{ secrets.PR_SSH_KEY }}
 
       # smoelius: The next use of `actions/cache` should match what is in ci.yml.
-      - uses: actions/cache@v3
+      - uses: actions/cache@v4
         with:
           path: |
             ~/.cargo/bin/