diff --git a/w1/channel.c b/w1/channel.c
index 0fb1e30..539fd54 100644
--- a/w1/channel.c
+++ b/w1/channel.c
@@ -239,7 +239,10 @@ CHAN *uChannelCreate (int cMax, int size, AC_HANDLE h0)
 
   pthread_condattr_t cattr;
   pthread_condattr_init(&cattr);
+#if defined(_POSIX_CLOCK_SELECTION) && (_POSIX_CLOCK_SELECTION > 0)
+  /* not available in Mac */
   pthread_condattr_setclock(&cattr, CLOCK_MONOTONIC);
+#endif
   pthread_cond_init(&(c->c.notFull),  &cattr);
   pthread_cond_init(&(c->c.notEmpty), &cattr);
   pthread_condattr_destroy(&cattr);
diff --git a/w1/scratch.c b/w1/scratch.c
index ab36c97..c968b68 100644
--- a/w1/scratch.c
+++ b/w1/scratch.c
@@ -90,7 +90,12 @@ SCR scratchCreate (const char *dirName, AC_HANDLE h)
   scr->blocks = arrayCreate (128, SCR_) ;
   if (! dirName || ! *dirName) dirName = "." ;
 
+#ifdef O_TMPFILE
   fd = open (dirName, O_TMPFILE | O_RDWR | O_CLOEXEC, 0600) ;  /* no O_CREAT, no name */
+#else
+  fd = -1;
+#endif
+
   if (fd < 0)            /* filesystem without O_TMPFILE: named file, then unlink */
     {
       char buf[4096] ;