diff --git a/dev-scheme/scm/files/scm-5.6.4-arrays.patch b/dev-scheme/scm/files/scm-5.6.4-arrays.patch
new file mode 100644
index 0000000000000..68bb6ef9a5069
--- /dev/null
+++ b/dev-scheme/scm/files/scm-5.6.4-arrays.patch
@@ -0,0 +1,12 @@
+diff '--color=auto' -Naur scm.old/scl.c scm/scl.c
+--- scm.old/scl.c	2026-04-18 21:41:05.718448466 +0300
++++ scm/scl.c	2026-04-18 21:41:28.657818441 +0300
+@@ -953,7 +953,7 @@
+   /* at this point, we have a legitimate floating point result */
+   if (lead_sgn==-1)  res = -res;
+   if (i==len)
+-# ifdef SINGLES
++# if defined  SINGLES && defined ARRAYS
+     return shrtp ? makflo(res) : makdbl(res, 0.0);
+ # else
+   return makdbl(res, 0.0);
diff --git a/dev-scheme/scm/scm-5.6.4-r1.ebuild b/dev-scheme/scm/scm-5.6.4-r1.ebuild
new file mode 100644
index 0000000000000..36ac6f0026bc7
--- /dev/null
+++ b/dev-scheme/scm/scm-5.6.4-r1.ebuild
@@ -0,0 +1,194 @@
+# Copyright 1999-2026 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+# Version magic thanks to masterdriverz and UberLord using bash array instead of tr
+trarr="0abcdefghi"
+MY_PV="$(ver_cut 1)${trarr:$(ver_cut 2):1}$(ver_cut 3)"
+MY_P=${PN}-${MY_PV}
+
+inherit toolchain-funcs flag-o-matic
+
+DESCRIPTION="SCM is a Scheme implementation from the author of slib"
+HOMEPAGE="https://people.csail.mit.edu/jaffer/SCM.html"
+SRC_URI="https://groups.csail.mit.edu/mac/ftpdir/scm/${MY_P}.zip"
+S=${WORKDIR}/${PN}
+
+LICENSE="LGPL-3"
+SLOT="0"
+KEYWORDS="~amd64 ~x86"
+IUSE="arrays bignums cautious dynamic-linking engineering-notation gsubr inexact ioext macro ncurses posix readline regex sockets unix"
+
+REQUIRED_USE="bignums? ( arrays inexact )"
+
+BDEPEND="app-arch/unzip"
+DEPEND=">=dev-scheme/slib-3.1.5
+	dev-util/cproto
+	ncurses? ( sys-libs/ncurses:0= )
+	readline? ( sys-libs/libtermcap-compat )"
+RDEPEND="${DEPEND}"
+
+PATCHES=(
+	"${FILESDIR}"/${P}-ported-fixes.patch
+	"${FILESDIR}"/${P}-c99.patch
+	"${FILESDIR}"/${P}-QA.patch
+	"${FILESDIR}"/${P}-ncurses.patch
+	"${FILESDIR}"/${P}-arrays.patch
+)
+
+src_prepare() {
+	default
+
+	sed \
+		-e "s|\"gcc\"|\"$(tc-getCC)\"|g" \
+		-e "s|\"ld\"|\"$(tc-getLD)\"|g" \
+		-e "s|\"-shared\"|\"-shared ${LDFLAGS}\"|g" \
+		-i ./build.scm || die
+}
+
+src_configure() {
+	append-cflags -std=gnu17
+	./configure \
+	--prefix="${EPREFIX}"/usr \
+	--mandir="${EPREFIX}"/usr/share/man \
+	--infodir="${EPREFIX}"/usr/share/info \
+	--datadir="${EPREFIX}"/usr/share \
+	--sysconfdir="${EPREFIX}"/etc \
+	--localstatedir="${EPREFIX}"/var/lib \
+	--libdir="${EPREFIX}"/usr/$(get_libdir) \
+	--docdir="${EPREFIX}"/usr/share/doc/${PF} \
+	--htmldir="${EPREFIX}"/usr/share/doc/${PF}/html \
+	|| die
+}
+
+src_compile() {
+	# SLIB is required to build SCM.
+	local slibpath="${EPREFIX}/usr/share/slib/"
+	if [ -n "$SCHEME_LIBRARY_PATH" ]; then
+		einfo "using SLIB $SCHEME_LIBRARY_PATH"
+	elif [ -d ${slibpath} ]; then
+		export SCHEME_LIBRARY_PATH=${slibpath}
+	fi
+
+	einfo "Making scmlit"
+	emake -j1 CC=$(tc-getCC) scmlit clean
+
+	einfo "Building scm"
+	local features=""
+	use arrays && features+="arrays"
+	use bignums && features+=" bignums"
+	use cautious && features+=" cautious"
+	use engineering-notation && features+=" engineering-notation"
+	use inexact && features+=" inexact"
+	use macro && features+=" macro"
+
+	( use readline ||
+	  use ncurses ||
+	  use regex ||
+	  use posix ||
+	  use ioext ||
+	  use gsubr ||
+	  use sockets ||
+	  use unix ||
+	  use dynamic-linking ) && features+=" dynamic-linking"
+
+	./build \
+		--compiler-options="${CFLAGS}" \
+		--linker-options="${LDFLAGS} -L${EPREFIX}/$(get_libdir)" \
+		-s "${EPREFIX}"/usr/$(get_libdir)/scm \
+		-F ${features:="none"} \
+		-h system \
+		-o scm || die
+
+	einfo "Building DLLs"
+	if use readline; then
+		./build \
+			--compiler-options="${CFLAGS}" \
+			--linker-options="${LDFLAGS}" \
+			-h system \
+			-F edit-line \
+			-t dll || die
+	fi
+	if use ncurses ; then
+		./build \
+			--compiler-options="${CFLAGS}" \
+			--linker-options="${LDFLAGS}" \
+			-F curses \
+			-h system \
+			-t dll || die
+	fi
+	if use regex ; then
+		./build \
+			--compiler-options="${CFLAGS}" \
+			--linker-options="${LDFLAGS}" \
+			-c rgx.c \
+			-h system \
+			-t dll || die
+	fi
+	if use gsubr ; then
+		./build \
+			--compiler-options="${CFLAGS}" \
+			--linker-options="${LDFLAGS}" \
+			-c gsubr.c \
+			-h system \
+			-t dll || die
+	fi
+	if use ioext ; then
+		./build \
+			--compiler-options="${CFLAGS}" \
+			--linker-options="${LDFLAGS}" \
+			-c ioext.c \
+			-h system \
+			-t dll || die
+	fi
+	if use posix; then
+		./build \
+			--compiler-options="${CFLAGS}" \
+			--linker-options="${LDFLAGS}" \
+			-c posix.c \
+			-h system \
+			-t dll || die
+	fi
+	if use sockets ; then
+		./build \
+			--compiler-options="${CFLAGS}" \
+			--linker-options="${LDFLAGS}" \
+			-c socket.c \
+			-h system \
+			-t dll || die
+	fi
+	if use unix ; then
+		./build \
+			--compiler-options="${CFLAGS}" \
+			--linker-options="${LDFLAGS}" \
+			-c unix.c \
+			-h system \
+			-t dll || die
+	fi
+}
+
+src_test() {
+	emake check
+}
+
+src_install() {
+	emake -j1 DESTDIR="${D}" man1dir="${EPREFIX}"/usr/share/man/man1/ \
+		install
+
+	doinfo scm.info
+	doinfo hobbit.info
+}
+
+regen_catalog() {
+	einfo "Regenerating catalog..."
+	scm -e "(require 'new-catalog)"
+}
+
+pkg_postinst() {
+	[[ -z ${ROOT} ]] && regen_catalog
+}
+
+pkg_config() {
+	regen_catalog
+}