diff --git a/src/lib/pio.pl b/src/lib/pio.pl
index c9653b72..7755918f 100644
--- a/src/lib/pio.pl
+++ b/src/lib/pio.pl
@@ -18,8 +18,6 @@ phrase_from_file(NT, File) :-
 
 phrase_from_file(NT, File, Options) :-
     (   var(File) -> instantiation_error(phrase_from_file/3)
-    ;   (\+ atom(File) ; File = []) ->
-            domain_error(source_sink, File, phrase_from_file/3)
     ;   must_be(list, Options),
         (   member(Var, Options), var(Var) -> instantiation_error(phrase_from_file/3)
         ;   member(type(Type), Options) ->