diff --git a/authsecret/1.0/IAuthSecret.hal b/authsecret/1.0/IAuthSecret.hal
index 6b573b3..9a0fd5f 100644
--- a/authsecret/1.0/IAuthSecret.hal
+++ b/authsecret/1.0/IAuthSecret.hal
@@ -42,5 +42,5 @@
      *
      * @param secret blob derived from the primary user's credential.
      */
-    primaryUserCredential(vec<uint8_t> secret);
+    oneway primaryUserCredential(vec<uint8_t> secret);
 };