diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4b6f9dd..4586e22 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -40,11 +40,10 @@ jobs:
         make
 
     - name: Install dependencies
+      # get path to composer.phar so we can run it with custom php.ini
       run: |
-        php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
-        php composer-setup.php
-        php -c php.ini composer.phar require --dev --ignore-platform-reqs phpunit/phpunit "4.8.36"
-        php -c php.ini composer.phar update --no-interaction
+        COMPOSER_PHAR=$(realpath $(which composer))
+        php -c php.ini $COMPOSER_PHAR update --no-interaction
 
   php-linux-x64:
     runs-on: ubuntu-latest
@@ -111,14 +110,14 @@ jobs:
       uses: cmb69/setup-php-sdk@v0.6
       with:
         version: '8.0'
-        arch: x64
+        arch: ${{ matrix.arch }}
         ts: ts
         deps: openssl
     - uses: ilammy/msvc-dev-cmd@v1
       with:
         arch: ${{ matrix.arch }}
         toolset: ${{steps.setup-php-sdk.outputs.toolset}}
-    # CMD only execute one commend per run
+    # not sure why CMD can't do multiline run statements
     - run: phpize
     - run: .\configure --with-prefix=${{steps.setup-php-sdk.outputs.prefix}} --enable-awscrt=shared --enable-cli --enable-openssl
     - run: nmake
diff --git a/composer.json b/composer.json
index 41670dd..65564c4 100644
--- a/composer.json
+++ b/composer.json
@@ -19,7 +19,7 @@
         "ext-awscrt": "*"
     },
     "require-dev": {
-        "phpunit/phpunit":"^5.6.3"
+        "phpunit/phpunit":"^4.8.35|^5.6.3"
     },
     "autoload": {
         "classmap": [