diff --git a/library/heaps.yap b/library/heaps.yap
index d7e7669e7..5a2e94e43 100644
--- a/library/heaps.yap
+++ b/library/heaps.yap
@@ -223,7 +223,7 @@ min_of_heap(t(_,_,t(Key1,Datum1,Lson,Rson)), Key1, Datum1, Key2, Datum2) :-
 	min_of_heap(Lson, Rson, Key2, Datum2).
 
 
-min_of_heap(t(Ka,Da,_,_), t(Kb,Db,_,_), Kb, Db) :-
+min_of_heap(t(Ka,_Da,_,_), t(Kb,Db,_,_), Kb, Db) :-
 	Kb @< Ka, !.
 min_of_heap(t(Ka,Da,_,_), _, Ka, Da).
 min_of_heap(t, t(Kb,Db,_,_), Kb, Db).
diff --git a/library/system.yap b/library/system.yap
index def416df4..156470324 100644
--- a/library/system.yap
+++ b/library/system.yap
@@ -289,7 +289,7 @@ win_popen(0, Command, ForReading, Result) :-
 	exec_command(Command, 0, ForWriting, 2, _, Result),
 	close(ForWriting).
 win_popen(1, Command, ForWriting, Result) :-
-	open_pipe_streams(Stream, ForWriting),
+	open_pipe_streams(ForReading, ForWriting),
 	exec_command(Command, ForReading, 1, 2, _, Result),
 	close(ForReading).
 	
@@ -358,7 +358,7 @@ get_shell0(Shell) :-
 	getenv('SHELL', Shell), !.
 get_shell0(Shell) :-
 	win, !,
-	getenv('COMSPEC', Shell0).
+	getenv('COMSPEC', Shell).
 get_shell0('/bin/sh').
 
 get_shell(Shell) :-