diff --git a/src/queue/join.ts b/src/queue/join.ts
index 6f8f7d47..d26c043e 100644
--- a/src/queue/join.ts
+++ b/src/queue/join.ts
@@ -9,7 +9,7 @@ import { mutex } from './mutex'
 
 export async function join(slotId: number, steamId: SteamId64): Promise<QueueSlotModel[]> {
   return await mutex.runExclusive(async () => {
-    logger.info({ steamId, slotId }, `join queue`)
+    logger.trace({ steamId, slotId }, `join queue`)
     const player = await collections.players.findOne({ steamId })
     if (!player) {
       throw new Error(`player does not exist: ${steamId}`)
@@ -19,6 +19,10 @@ export async function join(slotId: number, steamId: SteamId64): Promise<QueueSlo
     //   throw new Error(`player has not accepted rules`)
     // }
 
+    if (player.activeGame) {
+      throw new Error(`player has active game`)
+    }
+
     const state = await getState()
     if (![QueueState.waiting, QueueState.ready].includes(state)) {
       throw new Error('invalid queue state')
diff --git a/src/queue/views/html/queue-slot.tsx b/src/queue/views/html/queue-slot.tsx
index fef355ad..db8de1b4 100644
--- a/src/queue/views/html/queue-slot.tsx
+++ b/src/queue/views/html/queue-slot.tsx
@@ -45,7 +45,12 @@ export async function QueueSlot(props: { slot: QueueSlotModel; actor?: SteamId64
       />
     )
   } else if (props.actor) {
-    slotContent = <JoinButton slotId={props.slot.id} />
+    const actor = await collections.players.findOne({ steamId: props.actor })
+    if (!props.actor) {
+      throw new Error(`actor invalid: ${props.actor}`)
+    }
+
+    slotContent = <JoinButton slotId={props.slot.id} disabled={Boolean(actor?.activeGame)} />
   }
 
   return (
@@ -59,13 +64,14 @@ export async function QueueSlot(props: { slot: QueueSlotModel; actor?: SteamId64
   )
 }
 
-function JoinButton(props: { slotId: number }) {
+function JoinButton(props: { slotId: number; disabled: boolean }) {
   return (
     <button
       class="join-queue-button"
       name="join"
       value={`${props.slotId}`}
       aria-label={`Join queue on slot ${props.slotId}`}
+      disabled={props.disabled}
     >
       <IconPlus />
     </button>