1 files changed, 15 insertions, 0 deletions
diff --git a/klm/util/usage.cc b/klm/util/usage.cc
index 5fa3cc9a..8db375e1 100644
--- a/klm/util/usage.cc
+++ b/klm/util/usage.cc
@@ -21,6 +21,21 @@ namespace util {
 
 #if !defined(_WIN32) && !defined(_WIN64)
 namespace {
+
+// On Mac OS X, clock_gettime is not implemented.
+// CLOCK_MONOTONIC is not defined either.
+#ifdef __MACH__
+#define CLOCK_MONOTONIC 0
+
+int clock_gettime(int clk_id, struct timespec *tp) {
+  struct timeval tv;
+  gettimeofday(&tv, NULL);
+  tp->tv_sec = tv.tv_sec;
+  tp->tv_nsec = tv.tv_usec * 1000;
+  return 0;
+}
+#endif // __MACH__
+
 float FloatSec(const struct timeval &tv) {
   return static_cast<float>(tv.tv_sec) + (static_cast<float>(tv.tv_usec) / 1000000.0);
 }