diff --git a/include/mbedtls/entropy.h b/include/mbedtls/entropy.h
index 19e8e72..747aca4 100644
--- a/include/mbedtls/entropy.h
+++ b/include/mbedtls/entropy.h
@@ -255,6 +255,9 @@
 /**
  * \brief          Checkup routine
  *
+ *                 This module self-test also calls the entropy self-test,
+ *                 mbedtls_entropy_source_self_test();
+ *
  * \return         0 if successful, or 1 if a test failed
  */
 int mbedtls_entropy_self_test( int verbose );
@@ -263,6 +266,14 @@
 /**
  * \brief          Checkup routine
  *
+ *                 Verifies the integrity of the hardware entropy source
+ *                 provided by the function 'mbedtls_hardware_poll()'.
+ *
+ *                 Note this is the only hardware entropy source that is known
+ *                 at link time, and other entropy sources configured
+ *                 dynamically at runtime by the function
+ *                 mbedtls_entropy_add_source() will not be tested.
+ *
  * \return         0 if successful, or 1 if a test failed
  */
 int mbedtls_entropy_source_self_test( int verbose );