1 files changed, 1 insertions, 1 deletions
diff --git a/file.c b/file.c
index 6d99c3016d..816277049d 100644
--- a/file.c
+++ b/file.c
@@ -2167,7 +2167,7 @@ Init_File()
     rb_define_singleton_method(rb_cFile, "split",  rb_file_s_split, 1);
     rb_define_singleton_method(rb_cFile, "join",   rb_file_s_join, -2);
 
-#ifdef DOSISH
+#if defined DOSISH && !defined __CYGWIN__
     rb_define_const(rb_cFile, "ALT_SEPARATOR", rb_str_new2("\\"));
 #else
     rb_define_const(rb_cFile, "ALT_SEPARATOR", Qnil);