diff --git a/build-aux/configure-lib.sh b/build-aux/configure-lib.sh
index 2bfc0570..02a71430 100644
--- a/build-aux/configure-lib.sh
+++ b/build-aux/configure-lib.sh
@@ -217,6 +217,7 @@ lib/ctype/isalnum.c
 lib/ctype/isalpha.c
 lib/ctype/isascii.c
 lib/ctype/iscntrl.c
+lib/ctype/isgraph.c
 lib/ctype/isprint.c
 lib/ctype/ispunct.c
 lib/dirent/__getdirentries.c
diff --git a/include/ctype.h b/include/ctype.h
index 29578874..d0f2c7db 100644
--- a/include/ctype.h
+++ b/include/ctype.h
@@ -35,6 +35,7 @@ int isalpha (int c);
 int isascii (int c);
 int iscntrl (int c);
 int isdigit (int c);
+int isgraph (int c);
 int islower (int c);
 int isnumber (int c, int base);
 int isprint (int c);
diff --git a/lib/ctype/isgraph.c b/lib/ctype/isgraph.c
new file mode 100644
index 00000000..4d8458b7
--- /dev/null
+++ b/lib/ctype/isgraph.c
@@ -0,0 +1,27 @@
+/* -*-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 <ctype.h>
+
+int
+isgraph (int c)
+{
+  return c > 32 && c < 127;
+}