Index: lib/libthr/thread/thr_syscalls.c
===================================================================
--- lib/libthr/thread/thr_syscalls.c	(revision 189300)
+++ lib/libthr/thread/thr_syscalls.c	(working copy)
@@ -132,7 +132,9 @@
 int	__close(int);
 int	__connect(int, const struct sockaddr *, socklen_t);
 int	__fcntl(int, int,...);
+#ifdef SYSCALL_COMPAT
 extern int __fcntl_compat(int, int,...);
+#endif
 int	__fsync(int);
 int	__msync(void *, size_t, int);
 int	__nanosleep(const struct timespec *, struct timespec *);
@@ -253,7 +255,11 @@
 		ret = __sys_fcntl(fd, cmd);
 		break;
 	default:
+#ifdef SYSCALL_COMPAT
 		ret = __fcntl_compat(fd, cmd, va_arg(ap, void *));
+#else
+		ret = EOPNOTSUPP;
+#endif
 	}
 	va_end(ap);
 
Index: lib/libthr/Makefile
===================================================================
--- lib/libthr/Makefile	(revision 189300)
+++ lib/libthr/Makefile	(working copy)
@@ -51,4 +51,8 @@
 SYMLINKS+=lib${LIB}_p.a ${LIBDIR}/libpthread_p.a
 .endif
 
+.if !defined(WITHOUT_SYSCALL_COMPAT)
+CFLAGS+=-DSYSCALL_COMPAT
+.endif
+
 .include <bsd.lib.mk>