diff --git a/Makefile b/Makefile
index 9471e94..8fc0b43 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,7 @@
 
 TITLE = pkuthss
 EXAMPLE = thesis
-VERSION = 1.9.0
+VERSION = 1.9.1
 
 default: dist
 
diff --git a/doc/readme/ChangeLog.txt b/doc/readme/ChangeLog.txt
index f1d2705..20a1225 100644
--- a/doc/readme/ChangeLog.txt
+++ b/doc/readme/ChangeLog.txt
@@ -1,3 +1,20 @@
+2021-10-16, v1.9.1
+
+	* API changes:
+	- Support `mentorlines' like casthss.
+
+	* Changes to example template:
+	- thesis.tex: more obvious hints on `ugly', new note on `hidelinks'.
+	- copy.tex, origin.tex: minor update according to school requirements.
+
+	* Changes to package code:
+	- Merge common parts from pkuthss-*.def into pkuthss.def.
+	- Also "uglify" the keywords label.
+
+	* Misc:
+	- ChangeLog.txt: typo (thank @fjn308).
+	- Minor fixes and cosmetics.
+
 2021-03-29, v1.9.0
 
 	* API changes:
diff --git a/doc/readme/pkuthss.tex b/doc/readme/pkuthss.tex
index 365efa6..9a8e1de 100644
--- a/doc/readme/pkuthss.tex
+++ b/doc/readme/pkuthss.tex
@@ -51,7 +51,7 @@
 }
 
 \newif\ifblind\blindfalse
-\newcommand*{\docversion}{v1.9.0}
+\newcommand*{\docversion}{v1.9.1}
 \pkuthssinfo{
 	cthesisname = {本科生毕业论文}, ethesisname = {Undergraduate Thesis},
 	ctitle = {北京大学学位论文模版{\thssnl}pkuthss \docversion},
@@ -60,7 +60,7 @@
 		\texorpdfstring{\thssnl}{: }pkuthss \docversion%
 	},
 	cauthor = {盖茨波·钛·维克托}, eauthor = {Casper Ti.\ Vector},
-	date = {\zhdigits{2021}年\zhnumber{3}月},
+	date = {\zhdigits{2021}年\zhnumber{10}月},
 	studentid = {00910???}, school = {化学与分子工程学院},
 	cmajor = {应用化学}, emajor = {Applied Chemistry},
 	direction = {据说 Casper 自己也不知道}, mentorlines = {2},
diff --git a/tex/pkuthss-gbk.def b/tex/pkuthss-gbk.def
index bb09161..500b3bb 100644
--- a/tex/pkuthss-gbk.def
+++ b/tex/pkuthss-gbk.def
@@ -24,7 +24,7 @@
 %   pkuword.eps
 
 \ProvidesFile{pkuthss-gbk.def}
-	[2021/03/29 v1.9.0 Labels and captions in GBK encoding
+	[2021/10/16 v1.9.1 Labels and captions in GBK encoding
 		for the pkuthss document class]
 
 \def\label@ctitle{��Ŀ��}
diff --git a/tex/pkuthss-utf8.def b/tex/pkuthss-utf8.def
index afed37b..e1d9566 100644
--- a/tex/pkuthss-utf8.def
+++ b/tex/pkuthss-utf8.def
@@ -24,7 +24,7 @@
 %   pkuword.eps
 
 \ProvidesFile{pkuthss-utf8.def}
-	[2021/03/29 v1.9.0 Labels and captions in UTF-8 encoding
+	[2021/10/16 v1.9.1 Labels and captions in UTF-8 encoding
 		for the pkuthss document class]
 
 \def\label@ctitle{题目：}
diff --git a/tex/pkuthss.cls b/tex/pkuthss.cls
index 6ee4e69..e03a7bd 100644
--- a/tex/pkuthss.cls
+++ b/tex/pkuthss.cls
@@ -25,7 +25,7 @@
 
 \NeedsTeXFormat{LaTeX2e}[1995/12/01]
 \ProvidesClass{pkuthss}
-	[2021/03/29 v1.9.0 Peking University dissertation document class]
+	[2021/10/16 v1.9.1 Peking University dissertation document class]
 
 % eg. `\thss@int@boolopt{spacing}{true}' will expand to:
 %   \newif\ifthss@opt@spacing \thss@opt@spacingtrue
diff --git a/tex/pkuthss.def b/tex/pkuthss.def
index 9450851..3ffe300 100644
--- a/tex/pkuthss.def
+++ b/tex/pkuthss.def
@@ -23,7 +23,7 @@
 %   pkuword.eps
 
 \ProvidesFile{pkuthss.def}
-	[2021/03/29 v1.9.0 Labels and captions for the pkuthss document class]
+	[2021/10/16 v1.9.1 Labels and captions for the pkuthss document class]
 
 \def\label@ementor{Directed by\ }
 \def\euniversity{Peking University}