diff --git a/bitchat/Utils/MessageDeduplicator.swift b/bitchat/Utils/MessageDeduplicator.swift
index 27909ad4..d2fc489d 100644
--- a/bitchat/Utils/MessageDeduplicator.swift
+++ b/bitchat/Utils/MessageDeduplicator.swift
@@ -57,8 +57,10 @@ final class MessageDeduplicator {
         lock.lock()
         defer { lock.unlock() }
 
+        let now = Date()
+        cleanupOldEntries(before: now.addingTimeInterval(-maxAge))
+
         if lookup[id] == nil {
-            let now = Date()
             entries.append(Entry(id: id, timestamp: now))
             lookup[id] = now
             trimIfNeeded()
diff --git a/bitchatTests/MessageDeduplicatorTests.swift b/bitchatTests/MessageDeduplicatorTests.swift
index 6016d7a9..6db1117d 100644
--- a/bitchatTests/MessageDeduplicatorTests.swift
+++ b/bitchatTests/MessageDeduplicatorTests.swift
@@ -25,4 +25,20 @@ struct MessageDeduplicatorTests {
         #expect(deduplicator.contains("d"))
         #expect(deduplicator.contains("e"))
     }
+
+    @Test func markProcessed_cleansExpiredEntriesBeforeCountTrim() async {
+        let deduplicator = MessageDeduplicator(maxAge: 0.1, maxCount: 4)
+
+        deduplicator.markProcessed("expired")
+        try? await Task.sleep(nanoseconds: 200_000_000)
+
+        for id in ["b", "c", "d", "e"] {
+            deduplicator.markProcessed(id)
+        }
+
+        #expect(deduplicator.contains("b"))
+        #expect(deduplicator.contains("c"))
+        #expect(deduplicator.contains("d"))
+        #expect(deduplicator.contains("e"))
+    }
 }