diff --git a/dev-libs/libmcp23s17/Manifest b/dev-libs/libmcp23s17/Manifest
new file mode 100644
index 0000000..e8340c9
--- /dev/null
+++ b/dev-libs/libmcp23s17/Manifest
@@ -0,0 +1,20 @@
+-----BEGIN PGP SIGNED MESSAGE-----
+Hash: SHA256
+
+DIST libmcp23s17-0.3.3_p20150727.tar.gz 39997 BLAKE2B f6bf1e99525ecdeb72816f5a8acb3513ee62786387fcf6fdb7cf88392387a761f7f94fce534c6270d6a06962e5cfe4c3b05f11cc9e4f396262b000958a268dfa SHA512 ca49dfb6dddbed684b9990cf5c4abbc3c55aee0cdc24f32bf8249c37537ca97b56d8f7cc84ab71388c450525326dba99b87c393eb35a67b51b439afb0e526d7d
+-----BEGIN PGP SIGNATURE-----
+
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+=B3ee
+-----END PGP SIGNATURE-----
diff --git a/dev-libs/libmcp23s17/files/libmcp23s17-fix-build-system.patch b/dev-libs/libmcp23s17/files/libmcp23s17-fix-build-system.patch
new file mode 100644
index 0000000..74af4ca
--- /dev/null
+++ b/dev-libs/libmcp23s17/files/libmcp23s17-fix-build-system.patch
@@ -0,0 +1,45 @@
+--- a/Makefile	2015-07-27 11:40:07.000000000 +0200
++++ b/Makefile	2017-10-22 11:26:50.381365663 +0200
+@@ -1,11 +1,11 @@
+ PROJECT=mcp23s17
+ SOURCES=src/mcp23s17.c
+-LIBRARY=static
+-INCPATHS=
+-LIBPATHS=
+-LDFLAGS=
+-CFLAGS=-c -Wall
+-CC=gcc
++CC ?= gcc
++CFLAGS += -Wall
++LIBRARY=shared
++INCPATHS =
++LIBPATHS =
++LDFLAGS +=
+ 
+ # ------------ MAGIC BEGINS HERE -------------
+ 
+@@ -31,20 +31,20 @@
+     ifeq "$(LIBRARY)" "static"
+ 	ar rcs $(BINARY) $(OBJECTS)
+     else
+-	$(CC) $(LIBFLAGS) $(OBJECTS) $(LDFLAGS) -o $@
++	$(CC) $(CFLAGS) $(LIBFLAGS) $(OBJECTS) $(LDFLAGS) -o $@
+     endif
+ 
+ .c.o:
+-	$(CC) $(INCFLAGS) $(CFLAGS) -fPIC $< -o $@
++	$(CC) $(INCFLAGS) $(CFLAGS) $(LDFLAGS) -fPIC $< -o $@
+ 
+ distclean: clean
+ 	rm -f $(BINARY)
+ 
+ example: example.c
+-	gcc -o example example.c -Isrc/ -L. -lmcp23s17
++	$(CC) $(CFLAGS) $(LDFLAGS) -o example example.c -Isrc/ -L. -lmcp23s17
+ 
+ interrupt_example: interrupt_example.c
+-	gcc -o interrupt_example interrupt_example.c -Isrc/ -L. -lmcp23s17
++	$(CC) $(CFLAGS) $(LDFLAGS) -o interrupt_example interrupt_example.c -Isrc/ -L. -lmcp23s17
+ 
+ clean:
+ 	rm -f $(OBJECTS)
diff --git a/dev-libs/libmcp23s17/libmcp23s17-0.3.3_p20150727.ebuild b/dev-libs/libmcp23s17/libmcp23s17-0.3.3_p20150727.ebuild
new file mode 100644
index 0000000..2ca1ae9
--- /dev/null
+++ b/dev-libs/libmcp23s17/libmcp23s17-0.3.3_p20150727.ebuild
@@ -0,0 +1,41 @@
+# Copyright 1999-2018 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI="6"
+
+inherit toolchain-funcs
+
+DESCRIPTION="C library for accessing a MCP23S17 port expander"
+HOMEPAGE="https://github.com/piface/libmcp23s17/"
+
+if [[ ${PV} == "9999" ]]; then
+	inherit git-r3
+	EGIT_REPO_URI="https://github.com/piface/libmcp23s17.git"
+else
+	COMMIT_ID="f65a5e2fb2f705eb0a108e1f888da7dea3638c4b"
+	SRC_URI="https://github.com/piface/libmcp23s17/archive/${COMMIT_ID}.tar.gz -> ${P}.tar.gz"
+	S="${WORKDIR}/libmcp23s17-${COMMIT_ID}"
+	KEYWORDS="~arm"
+fi
+
+LICENSE="GPL-3"
+SLOT="0"
+KEYWORDS="~arm"
+IUSE=""
+
+PATCHES=( "${FILESDIR}"/${PN}-fix-build-system.patch )
+
+DEPEND=""
+RDEPEND="${DEPEND}"
+
+src_configure(){
+	default
+
+	tc-export CC
+}
+
+src_install(){
+	dolib ${PN}.so
+	doheader src/mcp23s17.h
+	einstalldocs
+}
diff --git a/dev-libs/libmcp23s17/metadata.xml b/dev-libs/libmcp23s17/metadata.xml
new file mode 100644
index 0000000..14d02b2
--- /dev/null
+++ b/dev-libs/libmcp23s17/metadata.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
+<pkgmetadata>
+	<maintainer type="person">
+		<email>holgersson@posteo.de</email>
+		<name>Nils Freydank</name>
+	</maintainer>
+</pkgmetadata>