diff --git a/src/passes/1-parser/pascaligo.ml b/src/passes/1-parser/pascaligo.ml
index 4d982fe78..4ca440d7e 100644
--- a/src/passes/1-parser/pascaligo.ml
+++ b/src/passes/1-parser/pascaligo.ml
@@ -55,13 +55,12 @@ module Errors =
       in Trace.error ~data:[] title message
   end
 
-let parse (module IO : IO) parser =
-  let module Unit = PreUnit (IO) in
+let parse (module Unit : ParserUnit.S) parser =
   let local_fail error =
     Trace.fail
     @@ Errors.generic
-    @@ Unit.format_error ~offsets:IO.options#offsets
-                      IO.options#mode error in
+    @@ Unit.format_error ~offsets:Unit.IO.options#offsets
+                        Unit.IO.options#mode error in
   match parser () with
     Stdlib.Ok semantic_value -> Trace.ok semantic_value
 
@@ -121,7 +120,9 @@ let parse (module IO : IO) parser =
                Hint: Change the name.\n",
               None, invalid))
 
-let parse_file source =
+let parse_file :
+      string -> (Unit.Parser.ast, string Region.reg) Stdlib.result =
+  fun source ->
   let module IO =
     struct
       let ext = PreIO.ext
diff --git a/src/passes/1-parser/wrapper.ml b/src/passes/1-parser/wrapper.ml
index 665933466..9b36b4b2c 100644
--- a/src/passes/1-parser/wrapper.ml
+++ b/src/passes/1-parser/wrapper.ml
@@ -6,7 +6,10 @@ module type IO =
     val options : EvalOpt.options
   end
 
-let parse_file generic_error (module Unit : ParserUnit.S) parse =
+let parse_file generic_error
+               (module Unit : ParserUnit.S)
+               (parse: unit -> (Unit.Parser.ast, string Region.reg) Stdlib.result)
+    : (Unit.Parser.ast, string Region.reg) Stdlib.result =
   let lib_path =
     match Unit.IO.options#libs with
         [] -> ""