diff --git a/sci-physics/fastjet-contrib/fastjet-contrib-9999.ebuild b/sci-physics/fastjet-contrib/fastjet-contrib-9999.ebuild
new file mode 100644
index 0000000000000..d97361a5c0bcb
--- /dev/null
+++ b/sci-physics/fastjet-contrib/fastjet-contrib-9999.ebuild
@@ -0,0 +1,61 @@
+# Copyright 2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit subversion toolchain-funcs
+
+MY_PN=fjcontrib
+MY_P=${MY_PN}-${PV}
+
+DESCRIPTION="3rd party extensions of FastJet."
+HOMEPAGE="https://fastjet.hepforge.org/contrib/"
+ESVN_REPO_URI="https://svn.hepforge.org/fastjetsvn/contrib/trunk"
+
+LICENSE="GPL-2"
+SLOT="0"
+KEYWORDS=""
+
+DEPEND=">=sci-physics/fastjet-3.4.1"
+RDEPEND="${DEPEND}"
+
+PATCHES=(
+	"${FILESDIR}"/${PN}-1.049-ar.patch
+	"${FILESDIR}"/${PN}-1.055-ar-part2.patch # https://github.com/fjcontrib/fjcontrib/issues/3
+)
+
+src_unpack() {
+	subversion_src_unpack
+	subversion_wc_info || die "subversion_wc_info fails."
+	# We need the .svn folder for fetching contributions => copy it
+	rsync -rlpgo "${ESVN_WC_PATH}/.svn" "${S}" || die "can't copy .svn."
+	cd "${S}" || die "svn should have created ${S}."
+	./scripts/update-contribs.sh || die "can't fetch contributions"
+}
+
+src_configure() {
+	tc-export CXX AR RANLIB
+	./configure \
+		--prefix="${ESYSROOT}/usr" \
+		--fastjet-config="${ESYSROOT}/usr/bin/fastjet-config" \
+		RANLIB="${RANLIB}" \
+		AR="${AR}" \
+		CXX="${CXX}" \
+		CFLAGS="${CFLAGS}" \
+		CXXFLAGS="${CXXFLAGS}" \
+		FFLAGS="${FFLAGS}" \
+		LDFLAGS="${LDFLAGS}" || die
+}
+
+src_compile() {
+	emake
+	emake fragile-shared
+}
+
+src_install() {
+	emake install PREFIX="${ED}/usr"
+	dolib.so libfastjetcontribfragile.so
+	# The name used for requesting this library varies
+	dosym libfastjetcontribfragile.so /usr/$(get_libdir)/libfastjetcontribfragile.so.0
+	dosym libfastjetcontribfragile.so /usr/$(get_libdir)/fastjetcontribfragile.so.0
+}