diff --git a/src/resources/calendars.js b/src/resources/calendars.js
index 7748670..c51151e 100644
--- a/src/resources/calendars.js
+++ b/src/resources/calendars.js
@@ -4,7 +4,7 @@ export const calendars = createResourceDescription(
   'calendars',
   {
     includes: ['sync_account'],
-    filters: ['id'],
+    filters: ['id', 'is_sync_availability'],
   },
   {
     events: createResourceDescription('events', {
diff --git a/src/resources/users.js b/src/resources/users.js
index 5e95998..ec505d1 100644
--- a/src/resources/users.js
+++ b/src/resources/users.js
@@ -17,6 +17,7 @@ export const users = createResourceDescription(
       'calendars',
       {
         includes: ['sync_accounts'],
+        filters: ['is_sync_availability'],
       },
       {
         events: createResourceDescription('events', {