diff --git a/__test__/components/Calendar.test.tsx b/__test__/components/Calendar.test.tsx
index 8417c68..50abad8 100644
--- a/__test__/components/Calendar.test.tsx
+++ b/__test__/components/Calendar.test.tsx
@@ -250,4 +250,21 @@ describe("calendar Availability search", () => {
 
     expect(spy).not.toHaveBeenCalledWith();
   });
+
+  it("BUGFIX: can untoggle all personnal calendars", () => {
+    renderWithProviders(<CalendarTestWrapper />, {
+      user: preloadedState.user,
+      calendars: {
+        list: { "user1/cal1": preloadedState.calendars.list["user1/cal1"] },
+        pending: false,
+      },
+    });
+
+    const checkbox = screen.getByLabelText("Calendar personnal");
+    expect(checkbox).toBeChecked();
+
+    fireEvent.click(checkbox); // toggle off
+
+    expect(checkbox).not.toBeChecked();
+  });
 });
diff --git a/src/components/Calendar/Calendar.tsx b/src/components/Calendar/Calendar.tsx
index 795e538..ea21eb3 100644
--- a/src/components/Calendar/Calendar.tsx
+++ b/src/components/Calendar/Calendar.tsx
@@ -100,18 +100,17 @@ export default function CalendarApp({
   const fetchedRangesRef = useRef<Record<string, string>>({});
 
   // Auto-select personal calendars when first loaded
+  const initialLoadRef = useRef(true);
+
   useEffect(() => {
-    if (
-      Object.keys(calendars).length > 0 &&
-      userId &&
-      selectedCalendars.length === 0
-    ) {
+    if (initialLoadRef.current && Object.keys(calendars).length > 0 && userId) {
       const personalCalendarIds = Object.keys(calendars).filter(
         (id) => id.split("/")[0] === userId
       );
       setSelectedCalendars(personalCalendarIds);
+      initialLoadRef.current = false;
     }
-  }, [calendars, userId, selectedCalendars.length]);
+  }, [calendars, userId]);
 
   const calendarRange = getCalendarRange(selectedDate);
 
diff --git a/src/components/Calendar/utils/calendarUtils.ts b/src/components/Calendar/utils/calendarUtils.ts
index 4852fb4..85ae9d8 100644
--- a/src/components/Calendar/utils/calendarUtils.ts
+++ b/src/components/Calendar/utils/calendarUtils.ts
@@ -94,7 +94,7 @@ export const updateCalsDetails = (
   });
 
   if (rangeKey !== previousRangeKey) {
-    selectedCalendars.forEach((id) => {
+    selectedCalendars?.forEach((id) => {
       dispatch(
         getCalendarDetailAsync({
           calId: id,