diff --git a/src/Symfony/Bridge/PhpUnit/DeprecationErrorHandler.php b/src/Symfony/Bridge/PhpUnit/DeprecationErrorHandler.php
index e016b40973..ff9502e23a 100644
--- a/src/Symfony/Bridge/PhpUnit/DeprecationErrorHandler.php
+++ b/src/Symfony/Bridge/PhpUnit/DeprecationErrorHandler.php
@@ -54,7 +54,11 @@ class DeprecationErrorHandler
             if (false === $mode) {
                 $mode = getenv('SYMFONY_DEPRECATIONS_HELPER');
             }
-            if (DeprecationErrorHandler::MODE_WEAK !== $mode && DeprecationErrorHandler::MODE_WEAK_VENDORS !== $mode && (!isset($mode[0]) || '/' !== $mode[0])) {
+            if (DeprecationErrorHandler::MODE_DISABLED !== $mode
+                && DeprecationErrorHandler::MODE_WEAK !== $mode
+                && DeprecationErrorHandler::MODE_WEAK_VENDORS !== $mode
+                && (!isset($mode[0]) || '/' !== $mode[0])
+            ) {
                 $mode = preg_match('/^[1-9][0-9]*$/', $mode) ? (int) $mode : 0;
             }