diff -ru procmail-3.22.orig/src/setid.c procmail-3.22/src/setid.c
--- procmail-3.22.orig/src/setid.c	2010-02-04 10:05:43 +0100
+++ procmail-3.22/src/setid.c	2010-02-04 10:11:18 +0100
@@ -15,7 +15,11 @@
      return EX_USAGE;
    }
   endpwent();
-  if(initgroups(argv[1],p->pw_gid)||setgid(p->pw_gid)||setuid(p->pw_uid))
+  if(
+#ifndef __INTERIX
+  	initgroups(argv[1],p->pw_gid)||
+#endif
+	setgid(p->pw_gid)||setuid(p->pw_uid))
      return EX_OSERR;
   if(fopen(CHECK_FILE,"r"))
    { struct stat stbuf;