Consistently check for __hpux__
@@ -140,7 +140,7 @@ bson_get_monotonic_time (void)
/* Despite it's name, this is in milliseconds! */
int64_t ticks = GetTickCount64 ();
return (ticks * 1000L);
-#elif defined(__hpux)
+#elif defined(__hpux__)
int64_t nanosec = gethrtime ();
return (nanosec / 1000UL);
#else
