diff --git a/lib/verifier.ml b/lib/verifier.ml
index a633fa3..d8254db 100644
--- a/lib/verifier.ml
+++ b/lib/verifier.ml
@@ -51,6 +51,7 @@ let verify_notes ?(print = true) pool notes =
            | Assert sql -> (
                match Datastore.(query (prepare con sql) []) with
                | Error msg -> failwithf "Error !assert: %s\n" msg
+               | Ok [] | Ok [ [ Null ] ] -> ()
                | Ok [ [ Int s ] ] ->
                    if s = 1 then () else failwithf "Assertion failed: %s" sql
                | _ -> failwith "Error !assert: invalid result"));