diff --git a/include/mbedtls/ssl_cache.h b/include/mbedtls/ssl_cache.h
index e358c6c..b1ea801 100644
--- a/include/mbedtls/ssl_cache.h
+++ b/include/mbedtls/ssl_cache.h
@@ -99,6 +99,11 @@
  *
  * \param data     SSL cache context
  * \param session  session to retrieve entry for
+ *
+ * \return                \c 0 on success.
+ * \return                #MBEDTLS_ERR_SSL_CACHE_ENTRY_NOT_FOUND if there is
+ *                        no cache entry with specified session ID found, or
+ *                        any other negative error code for other failures.
  */
 int mbedtls_ssl_cache_get(void *data, mbedtls_ssl_session *session);
 
@@ -108,6 +113,9 @@
  *
  * \param data     SSL cache context
  * \param session  session to store entry for
+ *
+ * \return                \c 0 on success.
+ * \return                A negative error code on failure.
  */
 int mbedtls_ssl_cache_set(void *data, const mbedtls_ssl_session *session);