diff --git a/.github/workflows/blueprint.yml b/.github/workflows/blueprint.yml
index 05cf5d3..47d9ea4 100644
--- a/.github/workflows/blueprint.yml
+++ b/.github/workflows/blueprint.yml
@@ -37,7 +37,7 @@ jobs:
         run: ~/.elan/bin/lake build Existence
 
       - name: Cache API docs
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: |
             .lake/build/doc/Aesop
diff --git a/.github/workflows/build-project.yml b/.github/workflows/build-project.yml
index 450a772..440159a 100644
--- a/.github/workflows/build-project.yml
+++ b/.github/workflows/build-project.yml
@@ -52,7 +52,7 @@ jobs:
           ~/.elan/bin/lake exe mk_all --check || echo "ERROR: please ensure that Existence.lean is up to date, for instance by running lake exe mk_all"
 
       - name: Cache build artifacts
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: .lake/build
           key: LakeBuild-${{ runner.os }}-${{ hashFiles('lean-toolchain') }}-${{ hashFiles('lake-manifest.json') }}