diff --git a/sys/zuse.hoon b/sys/zuse.hoon
index 45deef347..6acc4cbcd 100644
--- a/sys/zuse.hoon
+++ b/sys/zuse.hoon
@@ -6882,28 +6882,33 @@
       ::                                                ::  ++lef:yu:chrono:
       ++  lef                                           ::  leapsecond dates
         ^-  (list @da)
-        :~  ~2015.6.30..23.59.59   ~2012.6.30..23.59.59
-            ~2008.12.31..23.59.58  ~2005.12.31..23.59.57
-            ~1998.12.31..23.59.56  ~1997.6.30..23.59.55
-            ~1995.12.31..23.59.54  ~1994.6.30..23.59.53
-            ~1993.6.30..23.59.52   ~1992.6.30..23.59.51
-            ~1990.12.31..23.59.50  ~1989.12.31..23.59.49
-            ~1987.12.31..23.59.48  ~1985.6.30..23.59.47
-            ~1983.6.30..23.59.46   ~1982.6.30..23.59.45
-            ~1981.6.30..23.59.44   ~1979.12.31..23.59.43
-            ~1978.12.31..23.59.42  ~1977.12.31..23.59.41
-            ~1976.12.31..23.59.40  ~1975.12.31..23.59.39
-            ~1974.12.31..23.59.38  ~1973.12.31..23.59.37
-            ~1972.12.31..23.59.36  ~1972.6.30..23.59.35
+        :~  ~2016.12.31..23.59.59   ~2015.6.30..23.59.59
+            ~2012.6.30..23.59.59    ~2008.12.31..23.59.58
+            ~2005.12.31..23.59.57   ~1998.12.31..23.59.56
+            ~1997.6.30..23.59.55    ~1995.12.31..23.59.54
+            ~1994.6.30..23.59.53    ~1993.6.30..23.59.52
+            ~1992.6.30..23.59.51    ~1990.12.31..23.59.50
+            ~1989.12.31..23.59.49   ~1987.12.31..23.59.48
+            ~1985.6.30..23.59.47    ~1983.6.30..23.59.46
+            ~1982.6.30..23.59.45    ~1981.6.30..23.59.44
+            ~1979.12.31..23.59.43   ~1978.12.31..23.59.42
+            ~1977.12.31..23.59.41   ~1976.12.31..23.59.40
+            ~1975.12.31..23.59.39   ~1974.12.31..23.59.38
+            ~1973.12.31..23.59.37   ~1972.12.31..23.59.36
+            ~1972.6.30..23.59.35
         ==
-      ::                                                ::  ++les:yu:chrono:
-      ++  les                                           ::  leapsecond days
+      ::
+      ::  +les:yu:chrono: leapsecond days
+      ::
+      ::    https://www.ietf.org/timezones/data/leap-seconds.list
+      ::
+      ++  les
         ^-  (list @da)
-        :~  ~2015.7.1  ~2012.7.1  ~2009.1.1  ~2006.1.1  ~1999.1.1  ~1997.7.1
-            ~1996.1.1  ~1994.7.1  ~1993.7.1  ~1992.7.1  ~1991.1.1  ~1990.1.1
-            ~1988.1.1  ~1985.7.1  ~1983.7.1  ~1982.7.1  ~1981.7.1  ~1980.1.1
-            ~1979.1.1  ~1978.1.1  ~1977.1.1  ~1976.1.1  ~1975.1.1  ~1974.1.1
-            ~1973.1.1  ~1972.7.1
+        :~  ~2017.1.1  ~2015.7.1  ~2012.7.1  ~2009.1.1  ~2006.1.1  ~1999.1.1
+            ~1997.7.1  ~1996.1.1  ~1994.7.1  ~1993.7.1  ~1992.7.1  ~1991.1.1
+            ~1990.1.1  ~1988.1.1  ~1985.7.1  ~1983.7.1  ~1982.7.1  ~1981.7.1
+            ~1980.1.1  ~1979.1.1  ~1978.1.1  ~1977.1.1  ~1976.1.1  ~1975.1.1
+            ~1974.1.1  ~1973.1.1  ~1972.7.1
         ==
       --  ::yu
     --  ::chrono