diff --git a/test/boost_has_clock_gettime.ipp b/test/boost_has_clock_gettime.ipp
index 282f588b..cef1b050 100644
--- a/test/boost_has_clock_gettime.ipp
+++ b/test/boost_has_clock_gettime.ipp
@@ -17,6 +17,7 @@ void f()
     // this is never called, it just has to compile:
     timespec tp;
     int res = clock_gettime(CLOCK_REALTIME, &tp);
+    (void) &res;
 }
 
 int test()
diff --git a/test/boost_has_gettimeofday.ipp b/test/boost_has_gettimeofday.ipp
index 922a4f3e..547a8a2b 100644
--- a/test/boost_has_gettimeofday.ipp
+++ b/test/boost_has_gettimeofday.ipp
@@ -17,6 +17,7 @@ void f()
     // this is never called, it just has to compile:
     timeval tp;
     int res = gettimeofday(&tp, 0);
+    (void) &res;
 }
 
 int test()
diff --git a/test/boost_has_nanosleep.ipp b/test/boost_has_nanosleep.ipp
index 934cc4d9..1f8ad53b 100644
--- a/test/boost_has_nanosleep.ipp
+++ b/test/boost_has_nanosleep.ipp
@@ -15,9 +15,10 @@ namespace boost_has_nanosleep{
 void f()
 {
     // this is never called, it just has to compile:
-    timespec ts = {0};
+    timespec ts = {0, 0};
     timespec rm;
     int res = nanosleep(&ts, &rm);
+    (void) &res;
 }
 
 int test()
diff --git a/test/boost_has_sched_yield.ipp b/test/boost_has_sched_yield.ipp
index 92f30977..d6e91595 100644
--- a/test/boost_has_sched_yield.ipp
+++ b/test/boost_has_sched_yield.ipp
@@ -16,6 +16,7 @@ void f()
 {
     // this is never called, it just has to compile:
     int res = sched_yield();
+    (void) &res;
 }
 
 int test()