diff --git a/composer.required.json b/composer.required.json
index 0711c57b2..c68e07de5 100644
--- a/composer.required.json
+++ b/composer.required.json
@@ -29,6 +29,7 @@
     }
   },
   "extra": {
+    "composer-exit-on-patch-failure": true,
     "drupal-scaffold": {
       "initial": {
         "sites/default/default.services.yml": "sites/default/services.yml",
diff --git a/phing/tasks/deploy.xml b/phing/tasks/deploy.xml
index ff91194a2..f2d140168 100644
--- a/phing/tasks/deploy.xml
+++ b/phing/tasks/deploy.xml
@@ -182,7 +182,7 @@
             <include name="composer.lock"/>
           </fileset>
         </copy>
-        <exec dir="${deploy.dir}" command="export COMPOSER_EXIT_ON_PATCH_FAILURE=1; composer install --no-dev --no-interaction --optimize-autoloader" logoutput="true" checkreturn="true" level="${blt.exec_level}" passthru="true"/>
+        <exec dir="${deploy.dir}" command="composer install --no-dev --no-interaction --optimize-autoloader" logoutput="true" checkreturn="true" level="${blt.exec_level}" passthru="true"/>
       </then>
       <else>
         <echo>Dependencies will not be built because deploy.build-dependencies is not enabled.</echo>