diff --git a/pkg/cn-cbor/doc.txt b/pkg/cn-cbor/doc.txt
index ed68b593d4..07ac83099d 100644
--- a/pkg/cn-cbor/doc.txt
+++ b/pkg/cn-cbor/doc.txt
@@ -1,7 +1,7 @@
 /**
  * @defgroup pkg_cn-cbor cn-cbor
  * @ingroup  pkg
- * @ingroup  sys
+ * @ingroup  sys_serialization
  * @brief    A constrained node implementation of CBOR in C
  *
  * @see      https://github.com/cabo/cn-cbor