diff --git a/include/libmes.h b/include/libmes.h
index 1a311da5..18764668 100644
--- a/include/libmes.h
+++ b/include/libmes.h
@@ -27,6 +27,7 @@ int __mes_debug ();
 long abtol (char const** p, int base);
 char const* ntoab (long number, int base, int signed_p);
 char const* itoa (int number);
+char const* ltoa (long number);
 char const* utoa (unsigned long number);
 char const* ltoab (long x, int base);
 int atoi (char const *s);
diff --git a/lib/libmes.c b/lib/libmes.c
index e8ca8af3..fcf333cb 100644
--- a/lib/libmes.c
+++ b/lib/libmes.c
@@ -33,6 +33,7 @@
 #include <mes/ntoab.c>
 #include <mes/ltoab.c>
 #include <mes/itoa.c>
+#include <mes/ltoa.c>
 #include <mes/utoa.c>
 #include <mes/fdgetc.c>
 #include <mes/fdputc.c>
diff --git a/lib/mes/ltoa.c b/lib/mes/ltoa.c
new file mode 100644
index 00000000..82bed4d9
--- /dev/null
+++ b/lib/mes/ltoa.c
@@ -0,0 +1,27 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2018 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 <libmes.h>
+
+char const*
+ltoa (long x)
+{
+  return ntoab (x, 10, 1);
+}