diff --git a/packages/PLStream/pl-prologflag.c b/packages/PLStream/pl-prologflag.c
index 6460f5000..4d0b17616 100644
--- a/packages/PLStream/pl-prologflag.c
+++ b/packages/PLStream/pl-prologflag.c
@@ -1079,7 +1079,6 @@ initPrologFlags(void)
 	     ALLOW_VARNAME_FUNCTOR);
   setPrologFlag("toplevel_var_size", FT_INTEGER, 1000);
   setPrologFlag("toplevel_print_anon", FT_BOOL, TRUE, 0);
-  setPrologFlag("file_name_variables", FT_BOOL, FALSE, PLFLAG_FILEVARS);
 #ifdef __unix__
   setPrologFlag("unix", FT_BOOL|FF_READONLY, TRUE, 0);
 #endif
@@ -1105,6 +1104,7 @@ initPrologFlags(void)
   setPrologFlag("tty_control", FT_BOOL|FF_READONLY,
 	     truePrologFlag(PLFLAG_TTY_CONTROL), PLFLAG_TTY_CONTROL);
   setPrologFlag("encoding", FT_ATOM, stringAtom(encoding_to_atom(LD->encoding)));
+  setPrologFlag("file_name_variables", FT_BOOL, FALSE, PLFLAG_FILEVARS);
   setPrologFlag("fileerrors", FT_BOOL, TRUE, PLFLAG_FILEERRORS);
   setPrologFlag("readline", FT_BOOL/*|FF_READONLY*/, FALSE, 0);
 
diff --git a/pl/flags.yap b/pl/flags.yap
index ccef0bb31..f75b47339 100644
--- a/pl/flags.yap
+++ b/pl/flags.yap
@@ -60,7 +60,14 @@ yap_flag(encoding,X) :-
 yap_flag(encoding,X) :-
 	'$swi_set_prolog_flag'(encoding, X).
 
-% character encoding...
+% file_name_variables...
+yap_flag(file_name_variables,X) :-
+	var(X), !,
+	'$swi_current_prolog_flag'(file_name_variables, X).
+yap_flag(file_name_variables,X) :-
+	'$swi_set_prolog_flag'(file_name_variables, X).
+
+% fileerrors...
 yap_flag(fileerrors,X) :-
 	var(X), !,
 	'$swi_current_prolog_flag'(fileerrors, X).
@@ -813,6 +820,7 @@ yap_flag(dialect,yap).
 '$yap_system_flag'(encoding).
 '$yap_system_flag'(executable).
 %		V = fast  ;
+'$yap_system_flag'(file_name_variables).
 '$yap_system_flag'(fileerrors ).
 '$yap_system_flag'(float_format).
 %		V = float_mantissa_digits ;