diff --git a/include/mbedtls/md.h b/include/mbedtls/md.h
index 25e785e..edb37f1 100644
--- a/include/mbedtls/md.h
+++ b/include/mbedtls/md.h
@@ -79,8 +79,15 @@
 #endif
 
 /**
- * Opaque struct defined in md_wrap.h.
+ * Opaque struct.
+ *
+ * Constructed using either #mbedtls_md_info_from_string or
+ * #mbedtls_md_info_from_type.
+ *
+ * Fields can be accessed with #mbedtls_md_get_size,
+ * #mbedtls_md_get_type and #mbedtls_md_get_name.
  */
+/* Defined internally in library/md_wrap.h. */
 typedef struct mbedtls_md_info_t mbedtls_md_info_t;
 
 /**