diff --git a/include/mbedtls/md_internal.h b/include/mbedtls/md_internal.h
index 8cc8c5b..fe0feb3 100644
--- a/include/mbedtls/md_internal.h
+++ b/include/mbedtls/md_internal.h
@@ -52,10 +52,10 @@
     /** Name of the message digest */
     const char * name;
 
-    /** Output length of the digest function */
+    /** Output length of the digest function in bytes */
     int size;
 
-    /** Block length of the digest function */
+    /** Block length of the digest function in bytes */
     int block_size;
 
     /** Digest initialisation function */