diff --git a/sys/posix/include/semaphore.h b/sys/posix/include/semaphore.h
index c10d4f76af789774ece3af28501e2e1db1b12328..91dcaed3df5ed77dc9917cdf3ed9e18c656cb99a 100644
--- a/sys/posix/include/semaphore.h
+++ b/sys/posix/include/semaphore.h
@@ -34,6 +34,9 @@
 extern "C" {
 #endif
 
+/**
+ * @brief POSIX-specific semaphore type
+ */
 typedef sema_t sem_t;
 
 /**
diff --git a/sys/posix/pthread/include/pthread.h b/sys/posix/pthread/include/pthread.h
index df5d5d6092a2495a5e2cde425d1ed5d7c41b0650..daa6e3de3b5e2e2e353cdd50dfb8e8b313e3e143 100644
--- a/sys/posix/pthread/include/pthread.h
+++ b/sys/posix/pthread/include/pthread.h
@@ -22,9 +22,15 @@
 
 #include <time.h>
 
+/**
+ * @cond INTERNAL
+ */
 #ifndef __WITH_AVRLIBC__
 #define HAVE_MALLOC_H 1
 #endif
+/**
+ * @endcond
+ */
 
 #include "mutex.h"
 #include "sched.h"