diff --git a/src/Share.svelte b/src/Share.svelte
index c6f2b7e..ecace8e 100644
--- a/src/Share.svelte
+++ b/src/Share.svelte
@@ -9,6 +9,8 @@
     Toast
   } from 'sveltestrap';
 
+  import { ancestors } from './calendar';
+
   export let calendar = null;
   export let selectedCalendars = [];
 
@@ -33,6 +35,16 @@
       .finally((isToastOpen = true));
   };
 
+  const filter = calendars => {
+    let reduced = [];
+    calendars.forEach(c => {
+      if (!ancestors[c].some(p => calendars.includes(p))) {
+        reduced.push(c);
+      }
+    });
+    return reduced;
+  };
+
   const updateShareLink = () => {
     const loc = document.location;
     const search = new URLSearchParams();
@@ -41,7 +53,7 @@
     if (calendar !== null) {
       search.append('v', api.view.type);
 
-      selectedCalendars.forEach(c => search.append('c', c));
+      filter(selectedCalendars).forEach(c => search.append('c', c));
 
       search.append('d', api.getDate().toISOString());
     }
diff --git a/src/calendar.js b/src/calendar.js
index 902e020..a6a51df 100644
--- a/src/calendar.js
+++ b/src/calendar.js
@@ -176,6 +176,19 @@ export const calendarTree = {
   Divers: {}
 }
 
+const dfs = (p, t, l) => {
+  for (const [c, s] of Object.entries(t)) {
+    l[c] = p === null ? [] : [p, ...l[p]]
+    dfs(c, s, l)
+  }
+}
+
+export const ancestors = (() => {
+  let l = []
+  dfs(null, calendarTree, l)
+  return l
+})()
+
 export function getSubCalendars(name, tree = calendarTree) {
   let ret
   for (const [cal, subTree] of Object.entries(tree)) {