diff --git a/x11-libs/gtk3-nocsd/gtk3-nocsd-9999.ebuild b/x11-libs/gtk3-nocsd/gtk3-nocsd-9999.ebuild
new file mode 100644
index 0000000..23a48ed
--- /dev/null
+++ b/x11-libs/gtk3-nocsd/gtk3-nocsd-9999.ebuild
@@ -0,0 +1,33 @@
+# Copyright 2026 Shin'ya Minazuki
+EAPI=8
+
+inherit git-r3
+
+DESCRIPTION="A hack to disable client-side decorations for GTK+3 programs"
+HOMEPAGE="https://github.com/PCMan/gtk3-nocsd"
+EGIT_REPO_URI="https://github.com/PCMan/gtk3-nocsd"
+
+LICENSE="LGPL-2.1"
+SLOT="0"
+KEYWORDS=""
+
+DEPEND="
+	dev-libs/glib:2
+	dev-libs/gobject-introspection
+	x11-libs/gtk+:3
+"
+BDEPEND="
+	virtual/pkgconfig
+"
+RDEPEND="${DEPEND}"
+
+DOCS=( README.md )
+
+src_compile() {
+	# The assorted script uses the value of libdir for LD_PRELOAD
+	emake libdir="${EPREFIX}/usr/$(get_libdir)"
+}
+
+src_install() {
+	emake DESTDIR="${D}" prefix="${EPREFIX}/usr" libdir="${EPREFIX}/usr/$(get_libdir)" install
+}
diff --git a/x11-libs/gtk3-nocsd/metadata.xml b/x11-libs/gtk3-nocsd/metadata.xml
new file mode 100644
index 0000000..85a5f07
--- /dev/null
+++ b/x11-libs/gtk3-nocsd/metadata.xml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE pkgmetadata SYSTEM "https://www.gentoo.org/dtd/metadata.dtd">
+<pkgmetadata>
+	<maintainer type="person">
+		<email>shinyoukai@laidback.moe</email>
+		<name>Shin'ya Minazuki</name>
+	</maintainer>
+	<upstream>
+		<remote-id type="github">PCMan/gtk3-nocsd</remote-id>
+	</upstream>
+</pkgmetadata>