diff --git a/.github/workflows/continuous-integration.yml b/.github/workflows/continuous-integration.yml
index 69b13427..09bbbcfd 100644
--- a/.github/workflows/continuous-integration.yml
+++ b/.github/workflows/continuous-integration.yml
@@ -29,7 +29,7 @@ jobs:
         uses: shivammathur/setup-php@v1
         with:
           coverage: none
-          extensions: "json"
+          extensions: "mbstring, json"
           php-version: ${{ matrix.php-version }}
 
       - name: "Validate composer.json and composer.lock"
@@ -81,7 +81,7 @@ jobs:
         uses: shivammathur/setup-php@v1
         with:
           coverage: none
-          extensions: "json"
+          extensions: "mbstring, json"
           php-version: ${{ matrix.php-version }}
 
       - name: "Cache dependencies installed with composer"
@@ -122,7 +122,7 @@ jobs:
         uses: shivammathur/setup-php@v1
         with:
           coverage: none
-          extensions: "json"
+          extensions: "mbstring, json"
           php-version: ${{ matrix.php-version }}
 
       - name: "Cache dependencies installed with composer"
@@ -162,7 +162,7 @@ jobs:
         uses: shivammathur/setup-php@v1
         with:
           coverage: pcov
-          extensions: "json"
+          extensions: "mbstring, json"
           php-version: ${{ matrix.php-version }}
 
       - name: "Cache dependencies installed with composer"