diff --git a/.github/workflows/laravel.yml b/.github/workflows/laravel.yml
index 3d651850..1feeb7fa 100644
--- a/.github/workflows/laravel.yml
+++ b/.github/workflows/laravel.yml
@@ -46,9 +46,11 @@ jobs:
         run: "composer remove --dev symfony/* laravel/* --no-update --no-interaction"
       - name: "Require framework ${{ matrix.laravel-version}}"
         run: "composer require laravel/framework:${{ matrix.laravel-version}} --no-update --no-interaction --prefer-dist --prefer-stable"
-      - name: "Require Guzzle 6 ${{ matrix.lumen-version}}"
+      - name: "Replace guzzlehttp/guzzle with php-http/guzzle6-adapter for PHP 7.1"
         if: ${{ matrix.php-version == '7.1' }}
-        run: "composer require --dev php-http/guzzle6-adapter --no-update --no-interaction --prefer-dist --prefer-stable"
+        run: |
+          composer remove --dev guzzlehttp/guzzle --no-update --no-interaction
+          composer require --dev php-http/guzzle6-adapter --no-update --no-interaction
       - name: "Composer update with new requirements"
         run: "composer update --no-interaction --prefer-dist --prefer-stable"
       - name: "Run PHPUnit (Laravel) test suite"
diff --git a/.github/workflows/lumen.yml b/.github/workflows/lumen.yml
index 38a6eee6..f82f1033 100644
--- a/.github/workflows/lumen.yml
+++ b/.github/workflows/lumen.yml
@@ -50,9 +50,11 @@ jobs:
         run: "composer remove --dev symfony/* laravel/* --no-update --no-interaction"
       - name: "Require framework ${{ matrix.lumen-version}}"
         run: "composer require laravel/lumen:${{ matrix.lumen-version}} --no-update --no-interaction --prefer-dist --prefer-stable"
-      - name: "Require Guzzle 6 ${{ matrix.lumen-version}}"
+      - name: "Replace guzzlehttp/guzzle with php-http/guzzle6-adapter for PHP 7.1"
         if: ${{ matrix.php-version == '7.1' }}
-        run: "composer require --dev php-http/guzzle6-adapter --no-update --no-interaction --prefer-dist --prefer-stable"
+        run: |
+          composer remove --dev guzzlehttp/guzzle --no-update --no-interaction
+          composer require --dev php-http/guzzle6-adapter --no-update --no-interaction
       - name: "Composer update with new requirements"
         run: "composer update --no-interaction --prefer-dist --prefer-stable"
       - name: "Run PHPUnit (Lumen) test suite"
diff --git a/.github/workflows/symfony.yml b/.github/workflows/symfony.yml
index 599ebad8..3a1fd9ad 100644
--- a/.github/workflows/symfony.yml
+++ b/.github/workflows/symfony.yml
@@ -44,6 +44,11 @@ jobs:
       # See: https://github.com/composer/composer/issues/9561
       - name: "Remove existing requirements components (avoid conflicts)"
         run: "composer remove --dev symfony/* laravel/* --no-update --no-interaction"
+      - name: "Replace guzzlehttp/guzzle with php-http/guzzle6-adapter for PHP 7.1"
+        if: ${{ matrix.php-version == '7.1' }}
+        run: |
+          composer remove --dev guzzlehttp/guzzle --no-update --no-interaction
+          composer require --dev php-http/guzzle6-adapter --no-update --no-interaction
       - name: "Require Symfony ${{ matrix.symfony-version }}, Twig ${{ matrix.twig-version }}"
         run: "composer require symfony/symfony:${{ matrix.symfony-version }} twig/twig:${{ matrix.twig-version }} symfony/orm-pack:^2.0 symfony/twig-pack:^1.0 --no-update --no-interaction --prefer-dist --prefer-stable"
       - name: "Composer update with new requirements"
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 84d84be8..fd0809b5 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -44,6 +44,11 @@ jobs:
           php-version: "${{ matrix.php-version }}"
           tools: pecl
           extensions: ${{ matrix.extensions }}
+      - name: "Replace guzzlehttp/guzzle with php-http/guzzle6-adapter for PHP 7.1"
+        if: ${{ matrix.php-version == '7.1' }}
+        run: |
+          composer remove --dev guzzlehttp/guzzle --no-update --no-interaction
+          composer require --dev php-http/guzzle6-adapter --no-update --no-interaction
       - name: "Install lowest dependencies"
         if: ${{ matrix.dependencies == 'lowest' }}
         run: "composer update --prefer-lowest --prefer-dist --no-interaction --no-progress"