diff --git a/include/polarssl/timing.h b/include/polarssl/timing.h
index 1bc7351..203ee9a 100644
--- a/include/polarssl/timing.h
+++ b/include/polarssl/timing.h
@@ -58,6 +58,8 @@
 
 /**
  * \brief          Sleep for a certain amount of time
+ *
+ * \param          Delay in milliseconds
  */
 void m_sleep( int milliseconds );