diff --git a/src/Commands/Field/FieldTypesCommand.php b/src/Commands/Field/FieldTypesCommand.php
index 964d590..565519f 100644
--- a/src/Commands/Field/FieldTypesCommand.php
+++ b/src/Commands/Field/FieldTypesCommand.php
@@ -38,7 +38,7 @@ protected function execute(InputInterface $input, OutputInterface $output) {
 
     // get available fieldtypes
     foreach (\ProcessWire\wire('modules') as $module) {
-      if (preg_match('/^Fieldtype/', $module->name)) {
+      if (preg_match('/^Fieldtype/', (string)$module->name)) {
         $tools->writeDfList($module->name, substr($module->name, 9));
       }
     }