diff --git a/examples/riot_and_cpp/c_functions.h b/examples/riot_and_cpp/c_functions.h
index 3a4de5ab33..837b847e1d 100644
--- a/examples/riot_and_cpp/c_functions.h
+++ b/examples/riot_and_cpp/c_functions.h
@@ -22,6 +22,11 @@
 #ifndef C_FUNCTIONS_H
 #define C_FUNCTIONS_H
 
+
+/*
+ * all headers defining c functions must be marked as extern "C" when included
+ * into c++ sources
+ */
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/examples/riot_and_cpp/main.cpp b/examples/riot_and_cpp/main.cpp
index b53a356bb4..6bca2c4ab7 100644
--- a/examples/riot_and_cpp/main.cpp
+++ b/examples/riot_and_cpp/main.cpp
@@ -21,14 +21,9 @@
  * @author      DangNhat Pham-Huu <51002279@hcmut.edu.vn>
  */
 
-/*
- * all included headers defining c functions, i.e. all RIOT functions, must be marked as extern "C"
- */
-extern "C" {
 #include "thread.h"
 
 #include "c_functions.h"
-}
 
 #include <cstdio>
 #include <vector>