diff --git a/lib/ovo/ovo.ml b/lib/ovo/ovo.ml
index 9bb7b89c522b9621f722ca12ad2c362647df184c..d8949aa53730db8f99b04217fcf394bc64a2e928 100644
--- a/lib/ovo/ovo.ml
+++ b/lib/ovo/ovo.ml
@@ -48,15 +48,15 @@ let skip_ovo_header filename in_channel =
 let handle_ovo_basic_info in_channel =
   match handle_ovo_line ~f:Int.of_string in_channel with
   | [ dim ] -> Ok dim
-  | _ -> ovo_format_error "second"
-  | exception End_of_file -> ovo_format_error "second"
+  | _ -> ovo_format_error "first"
+  | exception End_of_file -> ovo_format_error "first"
 
 (* Skip unused flag. *)
 let handle_ovo_unused_flag in_channel =
   try
     let _ = Csv.next in_channel in
     Ok ()
-  with End_of_file -> ovo_format_error "forth"
+  with End_of_file -> ovo_format_error "second"
 
 (* Retrieves [filename] OVO model metadata and weights wrt OVO format
    specification, which is described here: