diff --git a/web/src/components/ActivityCalendar.tsx b/web/src/components/ActivityCalendar.tsx
index e5e130513..e2cf67c7d 100644
--- a/web/src/components/ActivityCalendar.tsx
+++ b/web/src/components/ActivityCalendar.tsx
@@ -41,7 +41,7 @@ const ActivityCalendar = (props: Props) => {
   const year = dayjs(monthStr).toDate().getFullYear();
   const month = dayjs(monthStr).toDate().getMonth() + 1;
   const dayInMonth = new Date(year, month, 0).getDate();
-  const firstDay = new Date(year, month - 1, 1).getDay() - weekStartDayOffset;
+  const firstDay = (new Date(year, month - 1, 1).getDay() - weekStartDayOffset) % 7;
   const lastDay = new Date(year, month - 1, dayInMonth).getDay() - weekStartDayOffset;
   const weekDays = WEEK_DAYS.slice(weekStartDayOffset).concat(WEEK_DAYS.slice(0, weekStartDayOffset));
   const maxCount = Math.max(...Object.values(data));
diff --git a/web/src/components/Settings/WorkspaceSection.tsx b/web/src/components/Settings/WorkspaceSection.tsx
index 7f718072d..45d782096 100644
--- a/web/src/components/Settings/WorkspaceSection.tsx
+++ b/web/src/components/Settings/WorkspaceSection.tsx
@@ -105,7 +105,7 @@ const WorkspaceSection = () => {
         </Link>
       </div>
       <div className="w-full flex flex-row justify-between items-center">
-        <span className="truncate">{t("setting.preference-section.default-memo-visibility")}</span>
+        <span className="truncate">Week start day</span>
         <Select
           className="!min-w-fit"
           value={workspaceGeneralSetting.weekStartDayOffset}
@@ -113,6 +113,7 @@ const WorkspaceSection = () => {
             handleWeekStartDayOffsetChanged(weekStartDayOffset || 0);
           }}
         >
+          <Option value={-1}>Saturday</Option>
           <Option value={0}>Sunday</Option>
           <Option value={1}>Monday</Option>
         </Select>