diff --git a/dev-dotnet/coco/coco-2014.12.25-r1.ebuild b/dev-dotnet/coco/coco-2014.12.25-r1.ebuild
new file mode 100644
index 0000000000000..11fd8e62cdb7e
--- /dev/null
+++ b/dev-dotnet/coco/coco-2014.12.25-r1.ebuild
@@ -0,0 +1,46 @@
+# Copyright 1999-2025 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+# Upstream did not tag this release.
+if [[ "${PV}" == "2014.12.25" ]] ; then
+	COMMIT_SHA="14be0314ae393569ab7abaf4e187f78e6d42b2fd"
+else
+	die 'Could not detect "COMMIT_SHA", please update the ebuild.'
+fi
+
+DOTNET_PKG_COMPAT="10.0"
+NUGET_PACKAGES=""
+
+inherit dotnet-pkg
+
+DESCRIPTION="The compiler generator Coco/R for C#"
+HOMEPAGE="https://github.com/boogie-org/coco/"
+
+if [[ "${PV}" == *9999* ]] ; then
+	inherit git-r3
+
+	EGIT_REPO_URI="https://github.com/boogie-org/${PN}.git"
+else
+	SRC_URI="https://github.com/boogie-org/${PN}/archive/${COMMIT_SHA}.tar.gz
+		-> ${P}.snapshot.gh.tar.gz"
+	S="${WORKDIR}/${PN}-${COMMIT_SHA}"
+
+	KEYWORDS="~amd64"
+fi
+
+LICENSE="GPL-2+"
+SLOT="0"
+
+DOTNET_PKG_PROJECTS=( Coco.csproj )
+
+dotnet-pkg_force-compat
+
+src_unpack() {
+	dotnet-pkg_src_unpack
+
+	if [[ -n "${EGIT_REPO_URI}" ]] ; then
+		git-r3_src_unpack
+	fi
+}