diff --git a/.github/workflows/checkin.yml b/.github/workflows/checkin.yml
index 2febfde2..c897d9a1 100644
--- a/.github/workflows/checkin.yml
+++ b/.github/workflows/checkin.yml
@@ -5,7 +5,7 @@ jobs:
   check_pr:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
 
     - name: "npm ci"
       run: npm ci
diff --git a/.github/workflows/cache-minimal.yml b/.github/workflows/disabled/cache-minimal.yml
similarity index 100%
rename from .github/workflows/cache-minimal.yml
rename to .github/workflows/disabled/cache-minimal.yml
diff --git a/.github/workflows/test-cache.yml b/.github/workflows/disabled/test-cache.yml
similarity index 93%
rename from .github/workflows/test-cache.yml
rename to .github/workflows/disabled/test-cache.yml
index 86fcf296..95c4f764 100644
--- a/.github/workflows/test-cache.yml
+++ b/.github/workflows/disabled/test-cache.yml
@@ -1,7 +1,3 @@
-# Changes to the v2 branch must be proposed via PRs in the branch
-# v3-next. This way we can check the action just as GHA is going to
-# use it.
-
 name: Test cache
 
 on:
diff --git a/.github/workflows/selftest.yml b/.github/workflows/selftest.yml
index fbce260b..31b6cf5c 100644
--- a/.github/workflows/selftest.yml
+++ b/.github/workflows/selftest.yml
@@ -1,7 +1,3 @@
-# Changes to the v2 branch must be proposed via PRs in the branch
-# v2-next. This way we can check the action just as GHA is going to
-# use it.
-
 name: Selftest
 
 on:
@@ -14,8 +10,11 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-12, macos-14, windows-latest]
+        os:     [ubuntu-latest, macos-12, macos-14, windows-latest]
         target: [stable, nightly, source]
+        msys2:  [true, false]
+        # A bit redundant for non-windows platforms, but let's keep things
+        # simple for the very rare times this workflow is run
 
     runs-on: ${{ matrix.os }}
 
@@ -28,6 +27,7 @@ jobs:
         uses: ./ # This uses the action code in the current PR
         if: matrix.target == 'stable'
         with:
+          msys2: ${{ matrix.msys2 }}
           cache: false
           # We test without cache, as caching is tested in a separate workflow.
           # This way we make sure the cache isn't hiding any issue.
@@ -36,6 +36,7 @@ jobs:
         uses: ./
         if: matrix.target == 'nightly'
         with:
+          msys2: ${{ matrix.msys2 }}
           version: nightly
           cache: false
 
@@ -43,6 +44,7 @@ jobs:
         uses: ./
         if: matrix.target == 'source'
         with:
+          msys2: ${{ matrix.msys2 }}
           branch: master
           cache: false
 
@@ -59,3 +61,13 @@ jobs:
       - run: alr -n version | grep "os:" | grep WINDOWS
         if: matrix.os == 'windows-latest'
         shell: bash
+
+      # Verify proper msys2 behavior
+
+      - run: alr -n version | grep "distribution:" | grep MSYS2
+        if: matrix.os == 'windows-latest' && matrix.msys2 == true
+        shell: bash
+
+      - run: alr -n version | grep "distribution:" | grep UNKNOWN
+        if: matrix.os == 'windows-latest' && matrix.msys2 == false
+        shell: bash
diff --git a/README.md b/README.md
index cf2d540b..f4d0c456 100644
--- a/README.md
+++ b/README.md
@@ -48,10 +48,10 @@ inputs:
     description: Arguments to pass to `alr toolchain` after setup.
     required: false
     default: 'gnat_native gprbuild'
-  toolchain_dir:
-    description: Location to install the toolchain under.
+  msys2:
+    description: Whether to install MSYS2 on Windows. When false, `msys2.do_not_install` will be set to true in alire's settings.
     required: false
-    default: ''
+    default: true
   cache:
     description: Whether to reuse a cached previous install.
     required: false
diff --git a/action.yml b/action.yml
index 2dae233d..fcfbf6b5 100644
--- a/action.yml
+++ b/action.yml
@@ -16,6 +16,10 @@ inputs:
     description: Arguments to pass to `alr toolchain` after setup.
     required: false
     default: 'gnat_native gprbuild'
+  msys2:
+    description: Whether to install MSYS2 on Windows. When false, `msys2.do_not_install` will be set to true in alire's settings.
+    required: false
+    default: true
   cache:
     description: Whether to reuse a cached previous install.
     required: false
@@ -50,7 +54,7 @@ runs:
       id: cache-key
       shell: bash
       run: |
-        echo "key=alr[1][${{ steps.find-hash.outputs.version }}][${{ inputs.toolchain }}][${{ runner.os }}][${{ runner.arch }}][${{ steps.find-hash.outputs.hash }}]" >> $GITHUB_OUTPUT
+        echo "key=alr[1][${{steps.find-hash.outputs.version}}][${{inputs.toolchain}}][msys2=${{inputs.msys2}}][${{runner.os}}][${{runner.arch}}][${{steps.find-hash.outputs.hash}}]" >> $GITHUB_OUTPUT
       # The first value in square brackets is to make the key unique for debugging
 
     - name: Reuse cached installation
@@ -107,7 +111,8 @@ runs:
       shell: bash
       run: echo "need=true" >> $GITHUB_OUTPUT
 
-    # Download a stable alr capable of installing a toolchain
+    # Download a stable alr capable of installing a toolchain. Avoid to install
+    # a msys2 at this point which is not needed and confuses later tests.
     - name: Install GNAT (I)
       if: steps.need-GNAT.outputs.need == 'true'
       shell: bash
@@ -118,6 +123,7 @@ runs:
         unzip -o alr-${alr_version}-bin-x86_64-${os_lower}.zip "bin/alr*" -d tmp_alr
         rm alr-${alr_version}-bin-x86_64-${os_lower}.zip
         echo "$(pwd -W 2>/dev/null || pwd)/tmp_alr/bin" >> $GITHUB_PATH
+        alr settings --global --set msys2.do_not_install true
 
     # Perform the actual `alr install` and remove the `alr` just used to avoid
     # conflicts with the `alr` being built.
diff --git a/lib/main.js b/lib/main.js
index 8054dcf2..f2d2080f 100644
--- a/lib/main.js
+++ b/lib/main.js
@@ -127,17 +127,22 @@ function run() {
         try {
             var version;
             var branch;
+            var msys2;
             var tool_args;
             if (process.argv[2]) { // e.g., node lib/script.js <json object>
                 const inputs = JSON.parse(process.argv[2]);
+                // Log the inputs for the record
+                console.log("Inputs: " + process.argv[2]);
                 version = inputs.version;
                 branch = inputs.branch;
+                msys2 = inputs.msys2 == "true";
                 tool_args = inputs.toolchain;
             }
             else {
                 // Old way in case this is fixed by GH
                 version = core.getInput('version');
                 branch = core.getInput('branch');
+                msys2 = core.getInput('msys2') == "true";
                 tool_args = core.getInput('toolchain');
             }
             // Install the requested version/branch unless cached
@@ -159,6 +164,18 @@ function run() {
                 yield exec.exec(`alr -n settings --global --set index.auto_update_asked true`);
                 console.log("Enabled index auto-refresh without further asking.");
             }
+            //  Disable msys2 installation if requested
+            if (process.platform == "win32") {
+                if (msys2) {
+                    //  Re-enable in case it was disabled during previous actions steps
+                    yield exec.exec(`alr -n settings --global --set msys2.do_not_install false`);
+                    console.log(`MSYS2 installation NOT disabled (msys2=${msys2})`);
+                }
+                else {
+                    yield exec.exec(`alr -n settings --global --set msys2.do_not_install true`);
+                    console.log(`MSYS2 installation DISABLED (msys2=${msys2})`);
+                }
+            }
             // And configure the toolchain
             if (tool_args.length > 0 && !cached) {
                 yield exec.exec(`alr -n toolchain ${tool_args != "--disable-assistant" ? "--select " : ""} ${tool_args}`);
diff --git a/src/main.ts b/src/main.ts
index 5f9d75bc..135155a4 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -103,17 +103,24 @@ async function run() {
     try {
         var version : string
         var branch  : string
+        var msys2   : boolean
         var tool_args : string
 
         if (process.argv[2]) { // e.g., node lib/script.js <json object>
             const inputs = JSON.parse(process.argv[2])
+
+            // Log the inputs for the record
+            console.log("Inputs: " + process.argv[2])
+
             version   = inputs.version
             branch    = inputs.branch
+            msys2     = inputs.msys2 == "true";
             tool_args = inputs.toolchain
         } else {
             // Old way in case this is fixed by GH
             version   = core.getInput('version');
             branch    = core.getInput('branch');
+            msys2     = core.getInput('msys2') == "true";
             tool_args = core.getInput('toolchain');
         }
 
@@ -140,6 +147,18 @@ async function run() {
             console.log("Enabled index auto-refresh without further asking.");
         }
 
+        //  Disable msys2 installation if requested
+        if (process.platform == "win32") {
+            if (msys2) {
+                //  Re-enable in case it was disabled during previous actions steps
+                await exec.exec(`alr -n settings --global --set msys2.do_not_install false`);
+                console.log(`MSYS2 installation NOT disabled (msys2=${msys2})`);
+            } else {
+                await exec.exec(`alr -n settings --global --set msys2.do_not_install true`);
+                console.log(`MSYS2 installation DISABLED (msys2=${msys2})`);
+            }
+        }
+
         // And configure the toolchain
         if (tool_args.length > 0 && !cached) {
             await exec.exec(`alr -n toolchain ${tool_args != "--disable-assistant" ? "--select " : ""} ${tool_args}`);