diff --git a/.github/workflows/check-commits.yml b/.github/workflows/check-commits.yml
index 64c8f29..82858c8 100644
--- a/.github/workflows/check-commits.yml
+++ b/.github/workflows/check-commits.yml
@@ -15,7 +15,7 @@ jobs:
     name: Check Modules
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions/setup-node@v3
         with:
           node-version: 18.x
@@ -30,7 +30,7 @@ jobs:
     name: Check whether or not transpilation is completed.
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions/setup-node@v3
         with:
           node-version: 18.x
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4e8f45c..7800753 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -19,11 +19,11 @@ jobs:
           - ubuntu-latest
           - macOS-latest
         swift-version:
-          - 5.7.2
-          - DEVELOPMENT-SNAPSHOT-2023-01-12-a
+          - 5.9.1
+          - DEVELOPMENT-SNAPSHOT-2023-10-18-a
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Install Swift.
         uses: ./
         with:
@@ -41,7 +41,7 @@ jobs:
           - macOS-latest
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Install Swift.
         uses: ./
         with:
diff --git a/swift-test-package/.swift-version b/swift-test-package/.swift-version
index 722fb61..9266671 100644
--- a/swift-test-package/.swift-version
+++ b/swift-test-package/.swift-version
@@ -1 +1 @@
-5.7.2
\ No newline at end of file
+5.9.1
\ No newline at end of file