diff --git a/website/server/controllers/api-v3/tasks.js b/website/server/controllers/api-v3/tasks.js
index 646c473e10..b0d16c65b5 100644
--- a/website/server/controllers/api-v3/tasks.js
+++ b/website/server/controllers/api-v3/tasks.js
@@ -681,12 +681,17 @@ api.updateTask = {
       task.group.managerNotes = sanitizedObj.managerNotes;
     }
 
-    // If the task was set to repeat monthly on a day of the month, and the start date was updated,
-    // the task will then need to be updated to repeat on the same day of the month as the new
-    // start date. For example, if the start date is updated to 7/2/2020, the daily should
+    // If the daily task was set to repeat monthly on a day of the month, and the start date was
+    // updated, the task will then need to be updated to repeat on the same day of the month as the
+    // new start date. For example, if the start date is updated to 7/2/2020, the daily should
     // repeat on the 2nd day of the month. It's possible that a task can repeat monthly on a
     // week of the month, in which case we won't update the repetition at all.
-    if (task.frequency === 'monthly' && task.daysOfMonth.length && task.startDate) {
+    if (
+      task.type === 'daily'
+      && task.frequency === 'monthly'
+      && task.daysOfMonth.length
+      && task.startDate
+    ) {
       task.daysOfMonth = [moment(task.startDate).date()];
     }
 
diff --git a/website/server/models/task.js b/website/server/models/task.js
index b83ab726c7..ed449bdf05 100644
--- a/website/server/models/task.js
+++ b/website/server/models/task.js
@@ -363,9 +363,9 @@ export const DailySchema = new Schema(_.defaults({
   },
   streak: { $type: Number, default: 0 },
   // Days of the month that the daily should repeat on
-  daysOfMonth: { $type: [Number], default: [] },
+  daysOfMonth: { $type: [Number], default: () => [] },
   // Weeks of the month that the daily should repeat on
-  weeksOfMonth: { $type: [Number], default: [] },
+  weeksOfMonth: { $type: [Number], default: () => [] },
   isDue: { $type: Boolean },
   nextDue: [{ $type: String }],
   yesterDaily: { $type: Boolean, default: true, required: true },