diff --git a/src/lib/ui/components/ServerCard.svelte b/src/lib/ui/components/ServerCard.svelte
index e710c7c..637a626 100644
--- a/src/lib/ui/components/ServerCard.svelte
+++ b/src/lib/ui/components/ServerCard.svelte
@@ -65,7 +65,8 @@
     const currentRound = $derived(!gameEndedAt ? (round !== undefined ? round : reportedRound) : null);
     const gameElapsed = $derived(gameStartedAt && !gameEndedAt ? elapsedSince(gameStartedAt, $uiNow) : null);
     const emptyElapsed = $derived(elapsedSince(inactiveSince, $uiNow));
-    const knownCapacity = $derived(capacity !== null && Number.isFinite(capacity) && capacity > 0 ? capacity : null);
+    // These lobbies have four slots when the live status omits the limit.
+    const displayCapacity = $derived(capacity !== null && Number.isSafeInteger(capacity) && capacity > 0 ? capacity : 4);
     const cardStyle = $derived(`view-transition-name: server-${name.replace(/[^a-z0-9_-]/gi, '-')};`);
 </script>
 
@@ -90,7 +91,7 @@
         {#if showMap}<p class="map-note">{health === 'online' ? 'Current map' : 'Last map'}: {mapLabel}</p>{/if}
         {#if health === 'online'}
             <dl class="metrics">
-                <div><dt>Players</dt><dd title={knownCapacity === null ? 'Capacity unavailable' : `${knownCapacity} player capacity`}>{players ?? '—'}<span class="capacity">/{knownCapacity ?? '?'}</span></dd></div>
+                <div><dt>Players</dt><dd title={`${displayCapacity} player capacity`}>{players ?? '—'}<span class="capacity">/{displayCapacity}</span></dd></div>
                 <div><dt>Round</dt><dd>{currentRound ?? '—'}</dd></div>
                 <div><dt>Match time</dt><dd>{gameElapsed ?? '—'}</dd></div>
             </dl>
diff --git a/tests/unit/ui-server-card.test.ts b/tests/unit/ui-server-card.test.ts
index c8e7733..97d2a18 100644
--- a/tests/unit/ui-server-card.test.ts
+++ b/tests/unit/ui-server-card.test.ts
@@ -29,11 +29,14 @@ describe('compact server cards', () => {
         expect(body).not.toMatch(/Last seen|Last reported|Zombies Classic|>Active</);
     });
 
-    it('keeps capacity unknown when unavailable and never invents a four-player limit', () => {
-        const body = html({ players: 2, capacity: null });
-        expect(body).toContain('title="Capacity unavailable"');
-        expect(body).toMatch(/>2<span[^>]*>\/\?<\/span>/);
-        expect(body).not.toContain('/4');
+    it('defaults to four lobby slots when capacity is unavailable, while preserving a reported limit', () => {
+        for (const capacity of [null, undefined, 0, -1, 4.5, NaN, Infinity]) {
+            const body = html({ players: 2, capacity });
+            expect(body).toContain('title="4 player capacity"');
+            expect(body).toMatch(/>2<span[^>]*>\/4<\/span>/);
+            expect(body).not.toContain('/?');
+        }
+        expect(html({ players: 2, capacity: 8 })).toMatch(/>2<span[^>]*>\/8<\/span>/);
     });
 
     it('uses the newest fresh report while respecting explicit round data and match boundaries', () => {