diff --git a/build-aux/configure-lib.sh b/build-aux/configure-lib.sh
index 6575c809..f8b3c28f 100644
--- a/build-aux/configure-lib.sh
+++ b/build-aux/configure-lib.sh
@@ -275,6 +275,7 @@ lib/stub/getlogin.c
 lib/stub/getpwnam.c
 lib/stub/getpwuid.c
 lib/stub/gmtime.c
+lib/stub/mktime.c
 lib/stub/pclose.c
 lib/stub/popen.c
 lib/stub/rand.c
diff --git a/include/time.h b/include/time.h
index dc05b69f..60cc0f44 100644
--- a/include/time.h
+++ b/include/time.h
@@ -59,6 +59,7 @@ struct timespec
 int clock_gettime (clockid_t clk_id, struct timespec *tp);
 struct tm *localtime (time_t const *timep);
 struct tm *gmtime (time_t const *time);
+int mktime (struct tm *broken_time);
 int nanosleep (struct timespec const *requested_time, struct timespec const *remaining);
 time_t time (time_t * tloc);
 
diff --git a/lib/stub/localtime.c b/lib/stub/localtime.c
index 3b060cc2..0382678d 100644
--- a/lib/stub/localtime.c
+++ b/lib/stub/localtime.c
@@ -1,6 +1,6 @@
 /* -*-comment-start: "//";comment-end:""-*-
  * GNU Mes --- Maxwell Equations of Software
- * Copyright © 2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ * Copyright © 2017,2018,2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
  *
  * This file is part of GNU Mes.
  *
@@ -31,5 +31,6 @@ localtime (time_t const *timep)
     eputs ("localtime stub\n");
   stub = 1;
   errno = 0;
-  return 0;
+  static struct tm zero = { 0 };
+  return &zero;
 }
diff --git a/lib/stub/mktime.c b/lib/stub/mktime.c
new file mode 100644
index 00000000..65e49acf
--- /dev/null
+++ b/lib/stub/mktime.c
@@ -0,0 +1,33 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2018,2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ *
+ * This file is part of GNU Mes.
+ *
+ * GNU Mes is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * GNU Mes is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <mes/lib.h>
+#include <time.h>
+
+int
+mktime (struct tm *broken_time)
+{
+  static int stub = 0;
+  if (__mes_debug () && !stub)
+    eputs ("mktime stub\n");
+  stub = 1;
+  errno = 0;
+  return 0;
+}