diff --git a/sim_timer.c b/sim_timer.c
index 5b05d00e..2a364cdf 100644
--- a/sim_timer.c
+++ b/sim_timer.c
@@ -175,7 +175,7 @@ return sim_os_msec () - stime;
 }
 
 #if defined(SIM_ASYNCH_IO)
-#ifdef NEED_CLOCK_REALTIME
+#ifdef NEED_CLOCK_GETTIME
 int clock_gettime(int clk_id, struct timespec *tp)
 {
 uint32 secs, ns, tod[2], unixbase[2] = {0xd53e8000, 0x019db1de};
@@ -247,7 +247,7 @@ Sleep (msec);
 return sim_os_msec () - stime;
 }
 
-#if defined(NEED_CLOCK_REALTIME)
+#if defined(NEED_CLOCK_GETTIME)
 int clock_gettime(int clk_id, struct timespec *tp)
 {
 t_uint64 now, unixbase;
@@ -338,7 +338,7 @@ treq.tv_nsec = (milliseconds % MILLIS_PER_SEC) * NANOS_PER_MILLI;
 return sim_os_msec () - stime;
 }
 
-#if defined(NEED_CLOCK_REALTIME)
+#if defined(NEED_CLOCK_GETTIME)
 int clock_gettime(int clk_id, struct timespec *tp)
 {
 struct timeval cur;
@@ -399,7 +399,7 @@ if (tim > SIM_IDLE_MAX)
 return tim;
 }
 #if !defined(_POSIX_SOURCE) && defined(SIM_ASYNCH_IO)
-#ifdef NEED_CLOCK_REALTIME
+#ifdef NEED_CLOCK_GETTIME
 typedef int clockid_t;
 int clock_gettime(clockid_t clk_id, struct timespec *tp)
 {
diff --git a/sim_timer.h b/sim_timer.h
index 1bf8aa42..ace58461 100644
--- a/sim_timer.h
+++ b/sim_timer.h
@@ -35,7 +35,14 @@
 
 #ifndef CLOCK_REALTIME
 #define CLOCK_REALTIME 1
-#define NEED_CLOCK_REALTIME 1
+#define NEED_CLOCK_GETTIME 1
+#ifndef HAVE_STRUCT_TIMESPEC
+#define HAVE_STRUCT_TIMESPEC 1
+struct timespec {
+        long tv_sec;
+        long tv_nsec;
+};
+#endif /* HAVE_STRUCT_TIMESPEC */
 int clock_gettime(int clock_id, struct timespec *tp);
 #endif