diff --git a/driver/prefs.c b/driver/prefs.c
index ab97ffa..cc04cc9 100644
--- a/driver/prefs.c
+++ b/driver/prefs.c
@@ -969,7 +969,10 @@ write_init_file (Display *dpy,
 	     sure that the bits actually land on the disk right away. */
           /* Update 2020: Apparently here in the future, this sometimes takes
              3+ seconds, so let's not. */
+/* Interix has no sync() or alike. */
+#ifndef __INTERIX
 	  /* sync(); */
+#endif
 
           status = 0;    /* wrote and renamed successfully! */
 	}
diff --git a/driver/setuid.c b/driver/setuid.c
index 3ac78e4..a2b9e15 100644
--- a/driver/setuid.c
+++ b/driver/setuid.c
@@ -136,9 +136,12 @@ set_ids_by_number (uid_t uid, gid_t gid, char **message_ret)
   if (uid == (uid_t) -1) uid = (uid_t) -2;
 
   errno = 0;
+
+#ifndef __INTERIX
   if (setgroups_needed_p (gid) &&
       setgroups (1, &gid) < 0)
     sgs_errno = errno ? errno : -1;
+#endif
 
   errno = 0;
   if (setgid (gid) != 0)