diff --git a/lib/Sync/functions.php b/lib/Sync/functions.php
index e113f58..875b16d 100644
--- a/lib/Sync/functions.php
+++ b/lib/Sync/functions.php
@@ -71,5 +71,9 @@ function flattenArgument($value): string
         return 'null';
     }
 
+    if (\is_bool($value)) {
+        return $value ? 'true' : 'false';
+    }
+
     return (string) $value;
 }