diff --git a/tests/std_tests/check_std_c_time.c b/tests/std_tests/check_std_c_time.c
index 4a7fecf50..923d804ca 100644
--- a/tests/std_tests/check_std_c_time.c
+++ b/tests/std_tests/check_std_c_time.c
@@ -1,4 +1,5 @@
 #include <string.h>
+#include <unistd.h>
 
 #include "support.h"
 
@@ -18,6 +19,21 @@ START_TEST (check_c_tspecdiff)
 }
 END_TEST
 
+START_TEST (check_c_tspecdiff_five)
+{
+  struct timespec start, finish, diff;
+
+  clock_gettime(CLOCK_REALTIME, &start);
+  sleep(5);
+  clock_gettime(CLOCK_REALTIME, &finish);
+
+  diff = c_tspecdiff(finish, start);
+
+  fail_unless(diff.tv_sec == 5, NULL);
+  fail_unless(diff.tv_nsec > 0, NULL);
+}
+END_TEST
+
 START_TEST (check_c_secdiff)
 {
   struct timespec start, finish;
@@ -28,7 +44,22 @@ START_TEST (check_c_secdiff)
 
   diff = c_secdiff(finish, start);
 
-  fail_unless(diff > 0.00 && diff < 1.00, NULL);
+  fail_unless(diff > 0.00 && diff < 1.00, "diff is %.2f", diff);
+}
+END_TEST
+
+START_TEST (check_c_secdiff_three)
+{
+  struct timespec start, finish;
+  double diff;
+
+  clock_gettime(CLOCK_REALTIME, &start);
+  sleep(3);
+  clock_gettime(CLOCK_REALTIME, &finish);
+
+  diff = c_secdiff(finish, start);
+
+  fail_unless(diff > 3.00 && diff < 4.00, "diff is %.2f", diff);
 }
 END_TEST
 
@@ -36,7 +67,9 @@ static Suite *make_std_c_suite(void) {
   Suite *s = suite_create("std:path:c_basename");
 
   create_case(s, "check_c_tspecdiff", check_c_tspecdiff);
+  create_case(s, "check_c_tspecdiff_five", check_c_tspecdiff_five);
   create_case(s, "check_c_secdiff", check_c_secdiff);
+  create_case(s, "check_c_secdiff_three", check_c_secdiff_three);
 
   return s;
 }