diff --git a/tests/data/test517 b/tests/data/test517
index 31b38b1a272d9b3a76e966900082117b2c73178d..48d8122e7c9f2363472304139a3fa432db1777f4 100644
--- a/tests/data/test517
+++ b/tests/data/test517
@@ -109,6 +109,7 @@ nothing
 80: 20110623 56:34:56 => -1
 81: 20111323 12:34:56 => -1
 82: 20110623 12:34:79 => -1
+83: Wed, 31 Dec 2008 23:59:60 GMT => 1230768000
 </stdout>
 
 # This test case previously testes an overflow case ("2094 Nov 6 =>
diff --git a/tests/libtest/lib517.c b/tests/libtest/lib517.c
index 8502e9521810815032fc25d21424732ddaf6d33b..ba49ec41ec641d9c9aaede226971184a31f60e9f 100644
--- a/tests/libtest/lib517.c
+++ b/tests/libtest/lib517.c
@@ -23,7 +23,7 @@
 
 #include "memdebug.h"
 
-static const char *dates[]={
+static const char * const dates[]={
   "Sun, 06 Nov 1994 08:49:37 GMT",
   "Sunday, 06-Nov-94 08:49:37 GMT",
   "Sun Nov  6 08:49:37 1994",
@@ -115,6 +115,7 @@ static const char *dates[]={
   "20110623 56:34:56",
   "20111323 12:34:56",
   "20110623 12:34:79",
+  "Wed, 31 Dec 2008 23:59:60 GMT", /* leap second */
   NULL
 };