diff --git a/2007.ics b/2007.ics
index 9681e30..67180b7 100644
--- a/2007.ics
+++ b/2007.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2008.ics b/2008.ics
index 7ec3517..5262b4b 100644
--- a/2008.ics
+++ b/2008.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2009.ics b/2009.ics
index d989422..e8d65ca 100644
--- a/2009.ics
+++ b/2009.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2010.ics b/2010.ics
index 85cf192..27f2634 100644
--- a/2010.ics
+++ b/2010.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2011.ics b/2011.ics
index e1b5490..3390a50 100644
--- a/2011.ics
+++ b/2011.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2012.ics b/2012.ics
index c9a02ca..b8b96cf 100644
--- a/2012.ics
+++ b/2012.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2013.ics b/2013.ics
index c1e7107..c8795d3 100644
--- a/2013.ics
+++ b/2013.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2014.ics b/2014.ics
index a1ddc04..614c414 100644
--- a/2014.ics
+++ b/2014.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2015.ics b/2015.ics
index c133c04..b6c8c1a 100644
--- a/2015.ics
+++ b/2015.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2016.ics b/2016.ics
index 2dbd039..7be891f 100644
--- a/2016.ics
+++ b/2016.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2017.ics b/2017.ics
index 48f9f66..de9decf 100644
--- a/2017.ics
+++ b/2017.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2018.ics b/2018.ics
index 613e169..6a79249 100644
--- a/2018.ics
+++ b/2018.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2019.ics b/2019.ics
index f647fa1..83d019c 100644
--- a/2019.ics
+++ b/2019.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2020.ics b/2020.ics
index a5b8b0d..f650b43 100644
--- a/2020.ics
+++ b/2020.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2021.ics b/2021.ics
index 13e1099..d8aa385 100644
--- a/2021.ics
+++ b/2021.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2022.ics b/2022.ics
index 622c480..a3e1776 100644
--- a/2022.ics
+++ b/2022.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2023.ics b/2023.ics
index a5cd435..d2f958e 100644
--- a/2023.ics
+++ b/2023.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2024.ics b/2024.ics
index 051b70e..0ffa56d 100644
--- a/2024.ics
+++ b/2024.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/2025.ics b/2025.ics
index 16f6b73..4a7f193 100644
--- a/2025.ics
+++ b/2025.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD
diff --git a/dev-requirements.txt b/dev-requirements.txt
index 31ffd97..3d26596 100644
--- a/dev-requirements.txt
+++ b/dev-requirements.txt
@@ -2,7 +2,7 @@
 requests==2.32.3
 beautifulsoup4==4.12.3
 tqdm==4.67.0
-icalendar==4.1.1
+icalendar==6.0.1
 
 # test
 pytest==8.3.3
diff --git a/holiday-cn.ics b/holiday-cn.ics
index de31d02..cc860bd 100644
--- a/holiday-cn.ics
+++ b/holiday-cn.ics
@@ -8,7 +8,7 @@ X-WR-CALNAME:中国法定节假日
 BEGIN:VTIMEZONE
 TZID:Asia/Shanghai
 BEGIN:STANDARD
-DTSTART;VALUE=DATE-TIME:19700101T000000
+DTSTART:19700101T000000
 TZOFFSETFROM:+0800
 TZOFFSETTO:+0800
 END:STANDARD