diff --git a/functions/api/events-team/events/new.ts b/functions/api/events-team/events/new.ts
index 2849e4e..a0b4366 100644
--- a/functions/api/events-team/events/new.ts
+++ b/functions/api/events-team/events/new.ts
@@ -5,12 +5,13 @@ export async function onRequestPost(context: RequestContext) {
   const now = new Date();
   const currentMonth = now.getUTCMonth();
   const currentYear = now.getUTCFullYear();
+  const lastDayOfMonth = new Date(currentYear, currentMonth, 0).getUTCDate();
 
   if (
     typeof day !== "number" ||
     day < 1 ||
     // Last day of that month
-    day > new Date(currentYear, currentMonth, 0).getUTCDate() ||
+    day > lastDayOfMonth ||
     // Stop people sending weird decimal days
     parseInt(day.toString()) !== day ||
     typeof details !== "string" ||
@@ -32,6 +33,32 @@ export async function onRequestPost(context: RequestContext) {
       400,
     );
 
+  if (type === "rotw") {
+    const weekRanges: { [k: number]: number } = {
+      0: 7,
+      1: 14,
+      2: 21,
+      3: 28,
+      4: 35,
+    };
+
+    const weekRange = Math.floor(day / 7);
+
+    const existingEventInRange = await context.env.D1.prepare(
+      "SELECT id FROM events WHERE day > ? AND day <= ? AND month = ? AND type = 'rotw' AND year = ?;",
+    )
+      .bind(
+        weekRanges[weekRange] - 7,
+        weekRanges[weekRange],
+        currentMonth,
+        currentYear,
+      )
+      .first();
+
+    if (existingEventInRange)
+      return jsonError("There is already an rotw for that week", 400);
+  }
+
   const id = `${now.getTime()}${crypto.randomUUID().replaceAll("-", "")}`;
 
   await context.env.D1.prepare(