diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 7c04b75..69e0661 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -35,3 +35,10 @@ jobs:
         shell: bash
         run: |
           echo "rzk-version=${{ steps.rzk-check.outputs.rzk-version }}"
+
+      - name: Run the action again, using previously installed rzk
+        uses: ./
+        with:
+          system-rzk: true
+          version: "must be ignored!"
+          files: ${{ matrix.files }}
diff --git a/README.md b/README.md
index 45b4d58..4998762 100644
--- a/README.md
+++ b/README.md
@@ -27,6 +27,7 @@ The following example runs `rzk typecheck` on all literate Rzk Markdown files in
 | ------------- | :------: | ---------------------------------------------------- | ------ | ----------------------------- |
 | `rzk-version` |    No    | `rzk` version to use, ex. `latest` or `v0.5.3`       | string | `latest`                      |
 | `files`       |    No    | Files to process, ex. `lib/**/*.rzk src/**/*.rzk.md` | string | Rely on local `rzk.yaml` file |
+| `system-rzk`  |    No    | Use `rzk` executable provided by the system          | string | `false`                       |
 
 ## Outputs
 
diff --git a/action.yml b/action.yml
index 7c9945d..9a9ef61 100644
--- a/action.yml
+++ b/action.yml
@@ -5,6 +5,10 @@ branding:
   icon: "triangle"  # 2-simplex? :)
 
 inputs:
+  system-rzk:
+    description: "Use system rzk (instead of downloading binaries)"
+    required: false
+    default: "false"
   rzk-version:
     description: "Version of Rzk to use (latest by default)"
     required: false
@@ -24,6 +28,7 @@ runs:
   steps:
     - name: 🔨 Install Rzk proof assistant
       uses: jaxxstorm/action-install-gh-release@v1.10.0
+      if: ${{ inputs.system-rzk }} == "false"
       with:
         repo: fizruk/rzk
         tag: ${{ inputs.rzk-version }}