Use the new HAVE_LSEEK64 define.
diff --git a/syscall.c b/syscall.c
index 5cdf052..2f73ba3 100644
--- a/syscall.c
+++ b/syscall.c
@@ -243,7 +243,7 @@
 
 OFF_T do_lseek(int fd, OFF_T offset, int whence)
 {
-#if SIZEOF_OFF64_T
+#ifdef HAVE_LSEEK64
 	off64_t lseek64();
 	return lseek64(fd, offset, whence);
 #else