diff --git a/.github/workflows/buildx.yml b/.github/workflows/buildx.yml
index 5c32648..ae4e672 100644
--- a/.github/workflows/buildx.yml
+++ b/.github/workflows/buildx.yml
@@ -59,7 +59,7 @@ jobs:
         run: |
           USE_VERSION=$PHP_VERSION
           if [ "$PHP_VERSION" == "8.6" ]; then
-            USE_VERSION="8.6.0alpha2"
+            USE_VERSION=$(cat unstable-tag)
           fi
           echo "name=$USE_VERSION" >> "$GITHUB_OUTPUT"
       - name: Build and push Docker image
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index d8388a1..d3e7579 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -48,9 +48,9 @@ jobs:
 
       - name: Build test image
         if: matrix.php-version == '8.6'
-        run: docker build -t php-base --build-arg PHP_VERSION=$PHP_VERSION .
-        env:
-          PHP_VERSION: '8.6.0alpha2'
+        run: |
+          PHP_VERSION=$(cat unstable-tag)
+          docker build -t php-base --build-arg PHP_VERSION=$PHP_VERSION .
 
       - name: Pull main image for size comparison
         id: pull_main
diff --git a/unstable-tag b/unstable-tag
new file mode 100644
index 0000000..8a5b208
--- /dev/null
+++ b/unstable-tag
@@ -0,0 +1 @@
+8.6.0alpha2