diff --git a/app-emacs/yc/files/yc-5.2.1-emacs-26.patch b/app-emacs/yc/files/yc-5.2.1-emacs-26.patch
new file mode 100644
index 0000000000000..19925c65c4546
--- /dev/null
+++ b/app-emacs/yc/files/yc-5.2.1-emacs-26.patch
@@ -0,0 +1,11 @@
+--- a/yc.el
++++ b/yc.el
+@@ -2071,7 +2071,7 @@
+ ;; 文節を指定しない場合、現在の文節が対象となる
+ ;; 読みを取得した文節はその読みをキャッシュする
+ ;; cut が 非nil の場合、指定文節以降の読みを削除する
+-(defun yc-yomi (&optional idx &optional cut)
++(defun yc-yomi (&optional idx cut)
+   (if (integerp idx)
+       (yc-put-bunsetsu-yomi idx (yc-get-bunsetsu-yomi idx cut) cut)
+     (yc-put-bunsetsu-yomi yc-mark (yc-get-bunsetsu-yomi yc-mark cut) cut)))
diff --git a/app-emacs/yc/yc-5.2.1.ebuild b/app-emacs/yc/yc-5.2.1.ebuild
index eb6992a1aa200..22ccd0a32304d 100644
--- a/app-emacs/yc/yc-5.2.1.ebuild
+++ b/app-emacs/yc/yc-5.2.1.ebuild
@@ -1,4 +1,4 @@
-# Copyright 1999-2017 Gentoo Foundation
+# Copyright 1999-2018 Gentoo Foundation
 # Distributed under the terms of the GNU General Public License v2
 
 EAPI="6"
@@ -16,6 +16,7 @@ IUSE=""
 
 RDEPEND="app-i18n/canna"
 
+ELISP_PATCHES="${P}-emacs-26.patch"
 SITEFILE="50${PN}-gentoo.el"
 
 src_install() {