diff --git a/include/sta/debug_serial.hpp b/include/sta/debug_serial.hpp
index 470bfed..8dd9904 100644
--- a/include/sta/debug_serial.hpp
+++ b/include/sta/debug_serial.hpp
@@ -30,7 +30,8 @@
  * @def STA_DEBUG_SERIAL_FORCE
  * @brief Force enable module.
  *
- * Enables debug output even if NDEBUG is defined.
+ * Enables debug output even if NDEBUG is defined
+ * or DEBUG is not defined.
  *
  * @ingroup staCoreBuildConfig
  */