diff --git a/src/dune_lexer.mli b/src/dune_lexer.mli
index 7b3c5eaf..2067c6c7 100644
--- a/src/dune_lexer.mli
+++ b/src/dune_lexer.mli
@@ -12,3 +12,5 @@ val first_line : Lexing.lexbuf -> first_line
 (** Parse the first line of a versioned file but do not fail if it
     doesn't start with [(lang ...)]. *)
 val maybe_first_line : Lexing.lexbuf -> first_line option
+
+val eof_reached : Lexing.lexbuf -> bool
diff --git a/src/dune_lexer.mll b/src/dune_lexer.mll
index b7ac50b8..603c9407 100644
--- a/src/dune_lexer.mll
+++ b/src/dune_lexer.mll
@@ -61,6 +61,10 @@ and to_eol = parse
     { ()
     }
 
+and eof_reached = parse
+  | eof { true  }
+  | ""  { false }
+
 {
   let first_line lb =
     match maybe_first_line lb with