diff --git a/src/main/kotlin/net/thauvin/erik/mobibot/Mobibot.kt b/src/main/kotlin/net/thauvin/erik/mobibot/Mobibot.kt
index 7186f7e..77be960 100644
--- a/src/main/kotlin/net/thauvin/erik/mobibot/Mobibot.kt
+++ b/src/main/kotlin/net/thauvin/erik/mobibot/Mobibot.kt
@@ -173,6 +173,7 @@ class Mobibot(nickname: String, val channel: String, logsDirPath: String, p: Pro
         event?.let {
             with(event.getBot<PircBotX>()) {
                 LinksMgr.twitter.notification("$nick disconnected from irc://$serverHostname")
+                seen.add(userChannelDao.getChannel(channel).users)
             }
         }
         LinksMgr.twitter.shutdown()
@@ -197,8 +198,10 @@ class Mobibot(nickname: String, val channel: String, logsDirPath: String, p: Pro
             with(event.getBot<PircBotX>()) {
                 if (user.nick == nick) {
                     LinksMgr.twitter.notification("$nick has joined ${event.channel.name} on irc://$serverHostname")
+                    seen.add(userChannelDao.getChannel(channel).users)
                 } else {
                     tell.send(event)
+                    seen.add(user.nick)
                 }
             }
         }
@@ -228,7 +231,13 @@ class Mobibot(nickname: String, val channel: String, logsDirPath: String, p: Pro
     }
 
     override fun onNickChange(event: NickChangeEvent?) {
-        event?.let { tell.send(event) }
+        event?.let {
+            tell.send(event)
+            if (!it.oldNick.equals(it.newNick, true)) {
+                seen.add(it.oldNick)
+            }
+            seen.add(it.newNick)
+        }
     }
 
     override fun onPart(event: PartEvent?) {
@@ -236,6 +245,7 @@ class Mobibot(nickname: String, val channel: String, logsDirPath: String, p: Pro
             with(event.getBot<PircBotX>()) {
                 if (user.nick == nick) {
                     LinksMgr.twitter.notification("$nick has left ${event.channel.name} on irc://$serverHostname")
+                    seen.add(userChannelDao.getChannel(channel).users)
                 } else {
                     seen.add(user.nick)
                 }
@@ -424,10 +434,10 @@ class Mobibot(nickname: String, val channel: String, logsDirPath: String, p: Pro
         addons.add(Ping())
         addons.add(RockPaperScissors())
         addons.add(StockQuote())
-        addons.add(Weather2())
-        addons.add(WorldTime())
         addons.add(War())
+        addons.add(Weather2())
         addons.add(WolframAlpha())
+        addons.add(WorldTime())
 
         // Sort the addons
         addons.names.sort()
diff --git a/src/main/kotlin/net/thauvin/erik/mobibot/Utils.kt b/src/main/kotlin/net/thauvin/erik/mobibot/Utils.kt
index 0812339..511afb1 100644
--- a/src/main/kotlin/net/thauvin/erik/mobibot/Utils.kt
+++ b/src/main/kotlin/net/thauvin/erik/mobibot/Utils.kt
@@ -214,7 +214,7 @@ object Utils {
             } catch (e: IOException) {
                 logger.error("An IO error occurred loading the ${description}.", e)
             } catch (e: ClassNotFoundException) {
-                logger.error("An error occurred loading the {$description}.", e)
+                logger.error("An error occurred loading the ${description}.", e)
             }
         }
         return default
diff --git a/src/main/kotlin/net/thauvin/erik/mobibot/commands/seen/NickComparator.kt b/src/main/kotlin/net/thauvin/erik/mobibot/commands/seen/NickComparator.kt
new file mode 100644
index 0000000..8e251b0
--- /dev/null
+++ b/src/main/kotlin/net/thauvin/erik/mobibot/commands/seen/NickComparator.kt
@@ -0,0 +1,44 @@
+/*
+ * SeenComparator.kt
+ *
+ * Copyright (c) 2004-2022, Erik C. Thauvin (erik@thauvin.net)
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ *   Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ *
+ *   Neither the name of this project nor the names of its contributors may be
+ *   used to endorse or promote products derived from this software without
+ *   specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package net.thauvin.erik.mobibot.commands.seen
+
+import java.io.Serializable
+
+class NickComparator: Comparator<String>, Serializable {
+    override fun compare(a: String, b: String): Int {
+        return a.lowercase().compareTo(b.lowercase())
+    }
+    companion object {
+        private const val serialVersionUID = 1L
+    }
+}
diff --git a/src/main/kotlin/net/thauvin/erik/mobibot/commands/seen/Seen.kt b/src/main/kotlin/net/thauvin/erik/mobibot/commands/seen/Seen.kt
index cb02cad..de7f70b 100644
--- a/src/main/kotlin/net/thauvin/erik/mobibot/commands/seen/Seen.kt
+++ b/src/main/kotlin/net/thauvin/erik/mobibot/commands/seen/Seen.kt
@@ -32,6 +32,7 @@
 
 package net.thauvin.erik.mobibot.commands.seen
 
+import com.google.common.collect.ImmutableSortedSet
 import net.thauvin.erik.mobibot.Utils.bot
 import net.thauvin.erik.mobibot.Utils.helpFormat
 import net.thauvin.erik.mobibot.Utils.loadData
@@ -39,13 +40,16 @@ import net.thauvin.erik.mobibot.Utils.saveData
 import net.thauvin.erik.mobibot.Utils.sendMessage
 import net.thauvin.erik.mobibot.commands.AbstractCommand
 import net.thauvin.erik.mobibot.commands.Info.Companion.toUptime
+import org.pircbotx.User
 import org.pircbotx.hooks.types.GenericMessageEvent
 import org.slf4j.Logger
 import org.slf4j.LoggerFactory
+import java.util.TreeMap
+
 
 class Seen(private val serialObject: String) : AbstractCommand() {
     private val logger: Logger = LoggerFactory.getLogger(Seen::class.java)
-    val seenNicks: MutableList<SeenNick> = mutableListOf()
+    val seenNicks = TreeMap<String, SeenNick>(NickComparator())
 
     override val name = "seen"
     override val help = listOf("To view when a nickname was last seen:", helpFormat("%c $name <nick>"))
@@ -53,6 +57,7 @@ class Seen(private val serialObject: String) : AbstractCommand() {
     override val isPublic = true
     override val isVisible = true
 
+
     override fun commandResponse(channel: String, args: String, event: GenericMessageEvent) {
         if (isEnabled()) {
             if (args.isNotBlank() && !args.contains(' ')) {
@@ -63,12 +68,11 @@ class Seen(private val serialObject: String) : AbstractCommand() {
                         return
                     }
                 }
-                seenNicks.forEach {
-                    if (it.nick.equals(args, true)) {
-                        val lastSeen = System.currentTimeMillis() - it.last
-                        event.sendMessage("${it.nick} was last seen on $channel ${lastSeen.toUptime()} ago.")
-                        return
-                    }
+                if (seenNicks.containsKey(args)) {
+                    val seenNick = seenNicks.getValue(args)
+                    val lastSeen = System.currentTimeMillis() - seenNick.lastSeen
+                    event.sendMessage("${seenNick.nick} was last seen on $channel ${lastSeen.toUptime()} ago.")
+                    return
                 }
                 event.sendMessage("I haven't seen $args on $channel lately.")
             } else {
@@ -79,15 +83,16 @@ class Seen(private val serialObject: String) : AbstractCommand() {
 
     fun add(nick: String) {
         if (isEnabled()) {
-            seenNicks.forEach {
-                if (it.nick.equals(nick, true)) {
-                    if (it.nick != nick) it.nick = nick
-                    it.last = System.currentTimeMillis()
-                    save()
-                    return
-                }
+            seenNicks[nick] = SeenNick(nick, System.currentTimeMillis())
+            save()
+        }
+    }
+
+    fun add(users: ImmutableSortedSet<User>) {
+        if (isEnabled()) {
+            users.forEach {
+                seenNicks[it.nick] = SeenNick(it.nick, System.currentTimeMillis())
             }
-            seenNicks.add(SeenNick(nick))
             save()
         }
     }
@@ -99,12 +104,14 @@ class Seen(private val serialObject: String) : AbstractCommand() {
     fun load() {
         if (isEnabled()) {
             @Suppress("UNCHECKED_CAST")
-            seenNicks += loadData(
-                serialObject,
-                mutableListOf<SeenNick>(),
-                logger,
-                "seen nicknames"
-            ) as MutableList<SeenNick>
+            seenNicks.putAll(
+                loadData(
+                    serialObject,
+                    TreeMap<String, SeenNick>(),
+                    logger,
+                    "seen nicknames"
+                ) as TreeMap<String, SeenNick>
+            )
         }
     }
 
diff --git a/src/main/kotlin/net/thauvin/erik/mobibot/commands/seen/SeenNick.kt b/src/main/kotlin/net/thauvin/erik/mobibot/commands/seen/SeenNick.kt
index 0211dcc..b53414d 100644
--- a/src/main/kotlin/net/thauvin/erik/mobibot/commands/seen/SeenNick.kt
+++ b/src/main/kotlin/net/thauvin/erik/mobibot/commands/seen/SeenNick.kt
@@ -34,7 +34,7 @@ package net.thauvin.erik.mobibot.commands.seen
 
 import java.io.Serializable
 
-data class SeenNick(var nick: String, var last: Long = System.currentTimeMillis()) : Serializable {
+data class SeenNick(val nick: String, val lastSeen: Long) : Serializable {
     companion object {
         private const val serialVersionUID = 1L
     }
diff --git a/src/test/kotlin/net/thauvin/erik/mobibot/commands/seen/SeenTest.kt b/src/test/kotlin/net/thauvin/erik/mobibot/commands/seen/SeenTest.kt
index 3e28f32..59fa2b7 100644
--- a/src/test/kotlin/net/thauvin/erik/mobibot/commands/seen/SeenTest.kt
+++ b/src/test/kotlin/net/thauvin/erik/mobibot/commands/seen/SeenTest.kt
@@ -35,6 +35,7 @@ package net.thauvin.erik.mobibot.commands.seen
 import assertk.assertThat
 import assertk.assertions.isEqualTo
 import assertk.assertions.isGreaterThan
+import assertk.assertions.isNotEqualTo
 import assertk.assertions.isTrue
 import org.testng.annotations.AfterClass
 import org.testng.annotations.BeforeClass
@@ -45,6 +46,7 @@ import kotlin.io.path.fileSize
 class SeenTest {
     private val tmpFile = kotlin.io.path.createTempFile(suffix = ".ser")
     private val seen = Seen(tmpFile.toAbsolutePath().toString())
+    private val nick = "ErikT"
 
     @BeforeClass
     fun saveTest() {
@@ -57,12 +59,21 @@ class SeenTest {
         tmpFile.deleteIfExists()
     }
 
-    @Test
+    @Test(priority = 1)
     fun loadTest() {
-        val nick = seen.seenNicks[0]
         seen.clear()
+        assertThat(seen.seenNicks.isEmpty(), "nicknames map is not empty").isTrue()
         seen.load()
-        assertThat(seen.seenNicks[0] == nick, "nick is different").isTrue()
+        assertThat(seen.seenNicks.containsKey(nick), "nick is missing").isTrue()
+    }
+
+    @Test
+    fun addTest() {
+        val last = seen.seenNicks[nick]?.lastSeen
+        seen.add(nick.lowercase())
+        assertThat(seen.seenNicks.size, "nick is duplicated").isEqualTo(1)
+        assertThat(seen.seenNicks[nick]?.lastSeen, "last seen is not different").isNotEqualTo(last)
+        assertThat(seen.seenNicks[nick]?.nick, "nick is not lowercase").isEqualTo(nick.lowercase())
     }
 
     @Test(priority = 10)
diff --git a/version.properties b/version.properties
index 70f832b..e4dfa98 100644
--- a/version.properties
+++ b/version.properties
@@ -1,9 +1,9 @@
 #Generated by the Semver Plugin for Gradle
-#Fri Sep 16 00:01:57 PDT 2022
-version.buildmeta=525
+#Fri Sep 16 10:29:48 PDT 2022
+version.buildmeta=542
 version.major=0
 version.minor=8
 version.patch=0
 version.prerelease=rc
 version.project=mobibot
-version.semver=0.8.0-rc+525
+version.semver=0.8.0-rc+542
diff --git a/website/index.html b/website/index.html
index 6904a5f..8b9831f 100644
--- a/website/index.html
+++ b/website/index.html
@@ -100,7 +100,7 @@
                 <div><code>mobibot: time UK</code></div>
                 <div><code>mobibot: time GMT</code></div>
             </li>
-            <li>Sending messages to people on join/activity:
+            <li>Sending messages to people on join/activity
                 <div><code>mobibot: tell nickname Give me a call when you see this.</code></div>
             </li>
             <li>Recapping public channel messages
@@ -109,6 +109,9 @@
             <li>Listing the users on the channel
                 <div><code>/msg mobibot users</code></div>
             </li>
+            <li>Viewing when a nickname was last seen
+                <div><code>/msg mobibot seen nickname</code></div>
+            </li>
             <li>Random jokes from <a href="http://www.icndb.com/">The Internet Chuck Norris Database</a>
                 <div><code>mobibot: joke</code></div>
             </li>