diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 501d17dbc..7ad82b690 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -144,9 +144,11 @@ jobs:
           if [[ "${{ matrix.extensions }}" == "optimal" ]]; then
             # Optimal.
             echo 'EXT=imap, mbstring, openssl, intl, ctype, filter, hash' >> $GITHUB_OUTPUT
+            echo 'COMPOSER_OPTIONS=' >> $GITHUB_OUTPUT
           else
             # Minimal.
             echo 'EXT=none, curl, dom, json, libxml, mbstring, tokenizer, xml, xmlwriter, ctype, filter, hash' >> $GITHUB_OUTPUT
+            echo 'COMPOSER_OPTIONS=--ignore-platform-req=ext-simplexml' >> $GITHUB_OUTPUT
           fi
 
       - name: Set up PHP
@@ -163,6 +165,7 @@ jobs:
         if: ${{ matrix.php != '8.4' }}
         uses: "ramsey/composer-install@v3"
         with:
+          composer-options: ${{ steps.set_extensions.outputs.COMPOSER_OPTIONS }}
           # Bust the cache at least once a month - output format: YYYY-MM.
           custom-cache-suffix: $(date -u "+%Y-%m")
 
@@ -170,7 +173,7 @@ jobs:
         if: ${{ matrix.php == '8.4' }}
         uses: "ramsey/composer-install@v3"
         with:
-          composer-options: --ignore-platform-reqs
+          composer-options: --ignore-platform-reqs ${{ steps.set_extensions.outputs.COMPOSER_OPTIONS }}
           # Bust the cache at least once a month - output format: YYYY-MM.
           custom-cache-suffix: $(date -u "+%Y-%m")