diff --git a/nptl/tst-cnd-basic.c b/nptl/tst-cnd-basic.c
index 84b7f5f647..eb2fb6a77e 100644
--- a/nptl/tst-cnd-basic.c
+++ b/nptl/tst-cnd-basic.c
@@ -31,8 +31,14 @@ static mtx_t mutex;
 static int
 signal_parent (void)
 {
+  /* Acquire the lock so that cnd_signal does not run until
+     cnd_timedwait has been called.  */
+  if (mtx_lock (&mutex) != thrd_success)
+    FAIL_EXIT1 ("mtx_lock failed");
   if (cnd_signal (&cond) != thrd_success)
     FAIL_EXIT1 ("cnd_signal");
+  if (mtx_unlock (&mutex) != thrd_success)
+    FAIL_EXIT1 ("mtx_unlock");
 
   thrd_exit (thrd_success);
 }
@@ -47,6 +53,9 @@ do_test (void)
   if (mtx_init (&mutex, mtx_plain) != thrd_success)
     FAIL_EXIT1 ("mtx_init failed");
 
+  if (mtx_lock (&mutex) != thrd_success)
+    FAIL_EXIT1 ("mtx_lock failed");
+
   if (thrd_create (&id, (thrd_start_t) signal_parent, NULL)
       != thrd_success)
     FAIL_EXIT1 ("thrd_create failed");
@@ -59,6 +68,9 @@ do_test (void)
   if (thrd_join (id, NULL) != thrd_success)
     FAIL_EXIT1 ("thrd_join failed");
 
+  if (mtx_unlock (&mutex) != thrd_success)
+    FAIL_EXIT1 ("mtx_unlock");
+
   mtx_destroy (&mutex);
   cnd_destroy (&cond);
 
diff --git a/nptl/tst-cnd-broadcast.c b/nptl/tst-cnd-broadcast.c
index 90d6843154..62a4ab5a39 100644
--- a/nptl/tst-cnd-broadcast.c
+++ b/nptl/tst-cnd-broadcast.c
@@ -17,6 +17,7 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <threads.h>
+#include <stdbool.h>
 #include <stdio.h>
 #include <unistd.h>
 
@@ -28,12 +29,16 @@ static cnd_t cond;
 /* Mutex to control wait on cond.  */
 static mtx_t mutex;
 
+/* Number of threads which have entered the cnd_wait region.  */
+static unsigned int waiting_threads;
+
 /* Code executed by each thread.  */
 static int
 child_wait (void* data)
 {
   /* Wait until parent thread sends broadcast here.  */
   mtx_lock (&mutex);
+  ++waiting_threads;
   cnd_wait (&cond, &mutex);
   mtx_unlock (&mutex);
 
@@ -61,7 +66,16 @@ do_test (void)
     }
 
   /* Wait for other threads to reach their wait func.  */
-  thrd_sleep (&((struct timespec){.tv_sec = 2}), NULL);
+  while (true)
+    {
+      mtx_lock (&mutex);
+      TEST_VERIFY (waiting_threads <= N);
+      bool done_waiting = waiting_threads == N;
+      mtx_unlock (&mutex);
+      if (done_waiting)
+	break;
+      thrd_sleep (&((struct timespec){.tv_nsec = 100 * 1000 * 1000}), NULL);
+    }
 
   mtx_lock (&mutex);
   if (cnd_broadcast (&cond) != thrd_success)
diff --git a/nptl/tst-cnd-timedwait.c b/nptl/tst-cnd-timedwait.c
index 45a1512940..7d8a8e3557 100644
--- a/nptl/tst-cnd-timedwait.c
+++ b/nptl/tst-cnd-timedwait.c
@@ -31,8 +31,14 @@ static mtx_t mutex;
 static int
 signal_parent (void *arg)
 {
+  /* Acquire the lock so that cnd_signal does not run until
+     cnd_timedwait has been called.  */
+  if (mtx_lock (&mutex) != thrd_success)
+    FAIL_EXIT1 ("mtx_lock failed");
   if (cnd_signal (&cond) != thrd_success)
     FAIL_EXIT1 ("cnd_signal failed");
+  if (mtx_unlock (&mutex) != thrd_success)
+    FAIL_EXIT1 ("mtx_unlock");
 
   thrd_exit (thrd_success);
 }
@@ -47,10 +53,15 @@ do_test (void)
     FAIL_EXIT1 ("cnd_init failed");
   if (mtx_init (&mutex, mtx_plain) != thrd_success)
     FAIL_EXIT1 ("mtx_init failed");
+  if (mtx_lock (&mutex) != thrd_success)
+    FAIL_EXIT1 ("mtx_lock failed");
 
   if (clock_gettime (CLOCK_REALTIME, &w_time) != 0)
     FAIL_EXIT1 ("clock_gettime failed");
-  w_time.tv_nsec += 150000;
+
+  /* This needs to be sufficiently long to prevent the cnd_timedwait
+     call from timing out.  */
+  w_time.tv_sec += 3600;
 
   if (thrd_create (&id, signal_parent, NULL) != thrd_success)
     FAIL_EXIT1 ("thrd_create failed");
@@ -61,6 +72,9 @@ do_test (void)
   if (thrd_join (id, NULL) != thrd_success)
     FAIL_EXIT1 ("thrd_join failed");
 
+  if (mtx_unlock (&mutex) != thrd_success)
+    FAIL_EXIT1 ("mtx_unlock");
+
   mtx_destroy (&mutex);
   cnd_destroy (&cond);
 
diff --git a/nptl/tst-mtx-timedlock.c b/nptl/tst-mtx-timedlock.c
index dcae828fb2..616db722eb 100644
--- a/nptl/tst-mtx-timedlock.c
+++ b/nptl/tst-mtx-timedlock.c
@@ -78,6 +78,11 @@ do_test (void)
   /* Tiny amount of time, to assure that if any thread finds it busy.
      It will receive thrd_timedout.  */
   wait_time.tv_nsec += 1;
+  if (wait_time.tv_nsec == 1000 * 1000 * 1000)
+    {
+      wait_time.tv_sec += 1;
+      wait_time.tv_nsec = 0;
+    }
 
   if (thrd_create (&id, child_add, NULL) != thrd_success)
     FAIL_EXIT1 ("thrd_create failed");
