diff --git a/build-aux/configure-lib.sh b/build-aux/configure-lib.sh
index 1a254437..ab3a580f 100644
--- a/build-aux/configure-lib.sh
+++ b/build-aux/configure-lib.sh
@@ -360,6 +360,7 @@ lib/string/strerror.c
 lib/string/strncat.c
 lib/string/strpbrk.c
 lib/string/strspn.c
+lib/string/strtok.c
 lib/stub/__cleanup.c
 lib/stub/asctime.c
 lib/stub/atan2.c
diff --git a/include/string.h b/include/string.h
index 60b2887e..cb60243a 100644
--- a/include/string.h
+++ b/include/string.h
@@ -48,6 +48,7 @@ char *strncpy (char *to, char const *from, size_t size);
 int strncmp (char const *, char const *, size_t);
 char *strrchr (char const *s, int c);
 char *strstr (char const *haystack, char const *needle);
+char *strtok (char *new_string, char const *delimiters);
 char *strlwr (char *string);
 char *strupr (char *string);
 
diff --git a/lib/string/strtok.c b/lib/string/strtok.c
new file mode 100644
index 00000000..0ab05f93
--- /dev/null
+++ b/lib/string/strtok.c
@@ -0,0 +1,42 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 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 <string.h>
+
+char *
+strtok (char *new_string, char const *delimiters)
+{
+  static char *mark;
+  if (new_string)
+    mark = new_string;
+  if (!*mark)
+    return 0;
+  while (strchr (delimiters, *mark))
+    mark++;
+  char *point = mark;
+  while (*mark && !strchr (delimiters, *mark))
+    mark++;
+  if (*mark)
+    {
+      *mark = 0;
+      mark++;
+    }
+  return point;
+}