diff --git a/src/utils.js b/src/utils.js
index 9fcd29a..037b69d 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -87,6 +87,15 @@ function parseBooleanOperand(value) {
   const lower = String(value).trim().toLowerCase();
   if (lower === 'yes') return true;
   if (lower === 'no') return false;
+  if (lower === 'true') return true;
+  if (lower === 'false') return false;
+  if (lower === '1') return true;
+  if (lower === '0') return false;
+  if (lower === 'on') return true;
+  if (lower === 'off') return false;
+  if (lower === 'y') return true;
+  if (lower === 'n') return false;
+  if (typeof value === 'boolean') return value;
   return undefined;
 }