diff --git a/src/Composer/Command/DiagnoseCommand.php b/src/Composer/Command/DiagnoseCommand.php
index fa5e9aa56..06a8a84af 100644
--- a/src/Composer/Command/DiagnoseCommand.php
+++ b/src/Composer/Command/DiagnoseCommand.php
@@ -678,6 +678,12 @@ EOT
             $warnings['onedrive'] = PHP_VERSION;
         }
 
+        if (extension_loaded('uopz')
+            && !(filter_var(ini_get('uopz.disable'), FILTER_VALIDATE_BOOLEAN)
+            || filter_var(ini_get('uopz.exit'), FILTER_VALIDATE_BOOLEAN))) {
+            $warnings['uopz'] = true;
+        }
+
         if (!empty($errors)) {
             foreach ($errors as $error => $current) {
                 switch ($error) {
@@ -791,6 +797,11 @@ EOT
                         $text .= "Upgrade your PHP ({$current}) to use this location with Composer.".PHP_EOL;
                         break;
 
+                    case 'uopz':
+                        $text = "The uopz extension ignores exit calls and may not work with all Composer commands.".PHP_EOL;
+                        $text .= "Disabling it when using Composer is recommended.";
+                        break;
+
                     default:
                         throw new \InvalidArgumentException(sprintf("DiagnoseCommand: Unknown warning type \"%s\". Please report at https://github.com/composer/composer/issues/new.", $warning));
                 }