diff --git a/src/ChangeLog b/src/ChangeLog
index bddaa88c..a2a62106 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,8 @@
 2005-04-08  Hrvoje Niksic  <hniksic@xemacs.org>
 
+	* ptimer.c (ptimer_init): In fact, _POSIX_MONOTONIC_CLOCK needs to
+	be >= 0.
+
 	* ptimer.c (ptimer_init): Check whether _POSIX_MONOTONIC_CLOCK is
 	defined instead of whether it's greater than 0.  glibc defines it
 	to 0, but still makes it available via sysconf.
diff --git a/src/ptimer.c b/src/ptimer.c
index 45a389a8..47980cfc 100644
--- a/src/ptimer.c
+++ b/src/ptimer.c
@@ -183,7 +183,7 @@ ptimer_init (void)
 {
   struct timespec res;
 
-#ifdef _POSIX_MONOTONIC_CLOCK
+#if _POSIX_MONOTONIC_CLOCK >= 0	           /* -1 means not supported */
   if (sysconf (_SC_MONOTONIC_CLOCK) > 0)
     posix_clock_id = CLOCK_MONOTONIC;
   else