diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 25d708a..575d061 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -57,7 +57,7 @@ jobs:
 
       - name: Stan build caching
         # note: not quite working since we use a development branch of Stan
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         id: stan-cache
         with:
           path: ./stan/
@@ -65,7 +65,7 @@ jobs:
 
       # we use the cache here to build the Stan models once for multiple interfaces
       - name: Set up test model cache
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         id: test-models
         with:
           path: ./test_models/
@@ -95,14 +95,14 @@ jobs:
           python-version: ${{ matrix.python-version }}
 
       - name: Restore Stan
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         id: stan-cache
         with:
           path: ./stan/
           key: ${{ runner.os }}-stan-${{ hashFiles('stan/src/stan/version.hpp') }}-v${{ env.CACHE_VERSION }}
 
       - name: Restore built models
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         id: test-models
         with:
           path: ./test_models/
@@ -156,13 +156,13 @@ jobs:
             any::posterior
 
       - name: Restore Stan
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: ./stan/
           key: ${{ runner.os }}-stan-${{ hashFiles('stan/src/stan/version.hpp') }}-v${{ env.CACHE_VERSION }}
 
       - name: Restore built models
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         id: test-models
         with:
           path: ./test_models/
@@ -205,14 +205,14 @@ jobs:
           channel: ${{ matrix.julia-version }}
 
       - name: Restore Stan
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         id: stan-cache
         with:
           path: ./stan/
           key: ${{ runner.os }}-stan-${{ hashFiles('stan/src/stan/version.hpp') }}-v${{ env.CACHE_VERSION }}
 
       - name: Restore built models
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         id: test-models
         with:
           path: ./test_models/