diff --git a/src/util.ts b/src/util.ts
index d4bd5a8..bc30938 100644
--- a/src/util.ts
+++ b/src/util.ts
@@ -5,7 +5,7 @@ export function isClassPath(pathOrGroup: ClassPath | ClassPathGroup | ClassPath[
 }
 
 export function isClassPathGroup(pathOrGroup: ClassPath | ClassPathGroup | ClassPath[]): pathOrGroup is ClassPathGroup {
-  return !this.isClassPath(pathOrGroup);
+  return !isClassPath(pathOrGroup);
 }
 
 /**