diff --git a/src/include/taler_mintdb_plugin.h b/src/include/taler_mintdb_plugin.h
index f5e61a7c3..74dd72b4c 100644
--- a/src/include/taler_mintdb_plugin.h
+++ b/src/include/taler_mintdb_plugin.h
@@ -740,7 +740,8 @@ struct TALER_MINTDB_Plugin
    *
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param sesssion database connection to use
-   * @param h_blind hash of the blinded message to be signed
+   * @param h_blind hash of the blinded coin to be signed (will match
+   *                `h_coin_envelope` in the @a collectable to be returned)
    * @param collectable corresponding collectable coin (blind signature)
    *                    if a coin is found
    * @return #GNUNET_SYSERR on internal error
diff --git a/src/mintdb/plugin_mintdb_postgres.c b/src/mintdb/plugin_mintdb_postgres.c
index e4d0f4d50..e32c29edc 100644
--- a/src/mintdb/plugin_mintdb_postgres.c
+++ b/src/mintdb/plugin_mintdb_postgres.c
@@ -1288,7 +1288,8 @@ postgres_reserves_in_insert (void *cls,
  *
  * @param cls the `struct PostgresClosure` with the plugin-specific state
  * @param session database connection to use
- * @param h_blind hash of the blinded message to be signed
+ * @param h_blind hash of the blinded coin to be signed (will match
+ *                `h_coin_envelope` in the @a collectable to be returned)
  * @param collectable corresponding collectable coin (blind signature)
  *                    if a coin is found
  * @return #GNUNET_SYSERR on internal error