diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 55abe8da..5a8d41c3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -43,10 +43,18 @@ jobs:
 
       # Package manager setup
       - name: Setup pnpm
-        if: matrix.pm == 'pnpm'
-        uses: pnpm/action-setup@fc06bc1257f339d1d5d8b3a19a8cae5388b55320 # v4
+        if: matrix.pm == 'pnpm' && matrix.node != '18.x'
+        uses: pnpm/action-setup@08c4be7e2e672a47d11bd04269e27e5f3e8529cb # v6.0.0
         with:
-          version: latest
+          # Keep an explicit pnpm major because this repo's packageManager is Yarn.
+          version: 10
+
+      - name: Setup pnpm (via Corepack)
+        if: matrix.pm == 'pnpm' && matrix.node == '18.x'
+        shell: bash
+        run: |
+          corepack enable
+          corepack prepare pnpm@9 --activate
 
       - name: Setup Yarn (via Corepack)
         if: matrix.pm == 'yarn'
@@ -79,6 +87,8 @@ jobs:
         if: matrix.pm == 'pnpm'
         id: pnpm-cache-dir
         shell: bash
+        env:
+          COREPACK_ENABLE_STRICT: '0'
         run: echo "dir=$(pnpm store path)" >> $GITHUB_OUTPUT
 
       - name: Cache pnpm
diff --git a/.github/workflows/reusable-test.yml b/.github/workflows/reusable-test.yml
index e30ae1bc..3d650434 100644
--- a/.github/workflows/reusable-test.yml
+++ b/.github/workflows/reusable-test.yml
@@ -35,10 +35,18 @@ jobs:
           node-version: ${{ inputs.node-version }}
 
       - name: Setup pnpm
-        if: inputs.package-manager == 'pnpm'
-        uses: pnpm/action-setup@fc06bc1257f339d1d5d8b3a19a8cae5388b55320 # v4
+        if: inputs.package-manager == 'pnpm' && inputs.node-version != '18.x'
+        uses: pnpm/action-setup@08c4be7e2e672a47d11bd04269e27e5f3e8529cb # v6.0.0
         with:
-          version: latest
+          # Keep an explicit pnpm major because this repo's packageManager is Yarn.
+          version: 10
+
+      - name: Setup pnpm (via Corepack)
+        if: inputs.package-manager == 'pnpm' && inputs.node-version == '18.x'
+        shell: bash
+        run: |
+          corepack enable
+          corepack prepare pnpm@9 --activate
 
       - name: Setup Yarn (via Corepack)
         if: inputs.package-manager == 'yarn'
@@ -70,6 +78,8 @@ jobs:
         if: inputs.package-manager == 'pnpm'
         id: pnpm-cache-dir
         shell: bash
+        env:
+          COREPACK_ENABLE_STRICT: '0'
         run: echo "dir=$(pnpm store path)" >> $GITHUB_OUTPUT
 
       - name: Cache pnpm