diff --git a/eco-core/core-plugin/src/main/kotlin/com/willfp/ecopets/pets/PetsGUI.kt b/eco-core/core-plugin/src/main/kotlin/com/willfp/ecopets/pets/PetsGUI.kt
index f90504f..71d4d8a 100644
--- a/eco-core/core-plugin/src/main/kotlin/com/willfp/ecopets/pets/PetsGUI.kt
+++ b/eco-core/core-plugin/src/main/kotlin/com/willfp/ecopets/pets/PetsGUI.kt
@@ -3,6 +3,8 @@ package com.willfp.ecopets.pets
 import com.willfp.eco.core.config.updating.ConfigUpdater
 import com.willfp.eco.core.gui.menu
 import com.willfp.eco.core.gui.menu.Menu
+import com.willfp.eco.core.gui.page.Page
+import com.willfp.eco.core.gui.page.PageChangeEvent
 import com.willfp.eco.core.gui.slot
 import com.willfp.eco.core.gui.slot.ConfigSlot
 import com.willfp.eco.core.gui.slot.FillerMask
@@ -21,17 +23,6 @@ import kotlin.math.min
 object PetsGUI {
     private lateinit var menu: Menu
     private val petAreaSlots = mutableListOf<Pair<Int, Int>>()
-    private const val pageKey = "page"
-
-    private fun getPage(menu: Menu, player: Player): Int {
-        val pages = ceil(Pets.values()
-            .filter { player.getPetLevel(it) > 0 }
-            .size.toDouble() / petAreaSlots.size).toInt()
-
-        val page = menu.getState(player, pageKey) ?: 1
-
-        return max(min(pages, page + 1), 1)
-    }
 
     @JvmStatic
     @ConfigUpdater
@@ -42,8 +33,8 @@ object PetsGUI {
         val bottomRightColumn = plugin.configYml.getInt("gui.pet-area.bottom-right.column")
 
         petAreaSlots.clear()
-        for (row in topLeftRow..bottomRightRow) {
-            for (column in topLeftColumn..bottomRightColumn) {
+        for (row in topLeftRow .. bottomRightRow) {
+            for (column in topLeftColumn .. bottomRightColumn) {
                 petAreaSlots.add(Pair(row, column))
             }
         }
@@ -55,31 +46,28 @@ object PetsGUI {
         val petInfoItemBuilder = { player: Player, _: Menu ->
             val pet = player.activePet
 
-            if (pet == null) {
-                ItemStackBuilder(Items.lookup(plugin.configYml.getString("gui.pet-info.no-active.item")))
+            pet?.getPetInfoIcon(player)
+                ?: ItemStackBuilder(Items.lookup(plugin.configYml.getString("gui.pet-info.no-active.item")))
                     .setDisplayName(plugin.configYml.getFormattedString("gui.pet-info.no-active.name"))
                     .addLoreLines(plugin.configYml.getFormattedStrings("gui.pet-info.no-active.lore"))
                     .build()
-            } else {
-                pet.getPetInfoIcon(player)
-            }
         }
 
         val petIconBuilder = { player: Player, menu: Menu, index: Int ->
-            val page = getPage(menu, player)
+            val page = menu.getPage(player)
 
             val unlockedPets = Pets.values()
                 .sortedByDescending { player.getPetLevel(it) }
                 .filter { player.getPetLevel(it) > 0 }
 
-            val pagedIndex = ((page - 1) * petAreaSlots.size) + index
+            val pagedIndex = page * petAreaSlots.size - petAreaSlots.size + index
 
             val pet = unlockedPets.getOrNull(pagedIndex)
             pet?.getIcon(player) ?: ItemStack(Material.AIR)
         }
 
         return menu(plugin.configYml.getInt("gui.rows")) {
-            setTitle(plugin.langYml.getString("menu.title"))
+            title = plugin.langYml.getString("menu.title")
 
             setMask(
                 FillerMask(
@@ -88,35 +76,30 @@ object PetsGUI {
                 )
             )
 
-            setSlot(
-                plugin.configYml.getInt("gui.pet-info.row"),
-                plugin.configYml.getInt("gui.pet-info.column"),
-                slot(petInfoItemBuilder) {
-                    onLeftClick { event, _, _ ->
-                        val player = event.whoClicked as Player
-                        player.activePet?.levelGUI?.open(player)
-                    }
+            onRender { player, menu ->
+                menu.setState(player, "ecopets", true)
+
+                if (menu.getPage(player) > menu.getMaxPage(player)) {
+                    menu.setState(player, Page.PAGE_KEY, 1)
                 }
-            )
+            }
 
             for ((index, pair) in petAreaSlots.withIndex()) {
                 val (row, column) = pair
-
-                setSlot(row, column, slot({ p, m -> petIconBuilder(p, m, index) }) {
-                    setUpdater { p, m, _ ->
-                        petIconBuilder(p, m, index)
+                setSlot(row, column, slot({ player, menu -> petIconBuilder(player, menu, index) }) {
+                    setUpdater { player, menu, _ ->
+                        petIconBuilder(player, menu, index)
                     }
 
                     onLeftClick { event, _, _ ->
                         val player = event.whoClicked as Player
-
-                        val page = getPage(menu, player)
+                        val page = menu.getPage(player)
 
                         val unlockedPets = Pets.values()
                             .sortedByDescending { player.getPetLevel(it) }
                             .filter { player.getPetLevel(it) > 0 }
 
-                        val pagedIndex = ((page - 1) * petAreaSlots.size) + index
+                        val pagedIndex = page * petAreaSlots.size - petAreaSlots.size + index
 
                         val pet = unlockedPets.getOrNull(pagedIndex) ?: return@onLeftClick
 
@@ -134,6 +117,8 @@ object PetsGUI {
                 })
             }
 
+            // I do this for backwards compatibility because with PageChanger if you don't have any more pages, the item will disappear and this would require an update of the config for all users
+            // This is terrible imo, but everything for compatibility!
             setSlot(
                 plugin.configYml.getInt("gui.prev-page.location.row"),
                 plugin.configYml.getInt("gui.prev-page.location.column"),
@@ -141,14 +126,19 @@ object PetsGUI {
                     ItemStackBuilder(Items.lookup(plugin.configYml.getString("gui.prev-page.item")))
                         .setDisplayName(plugin.configYml.getString("gui.prev-page.name"))
                         .build()
-                ) {
-                    onLeftClick { event, _, menu ->
+                )
+                {
+                    onLeftClick { event, _, _ ->
                         val player = event.whoClicked as Player
-                        val page = getPage(menu, player)
+                        val page = menu.getPage(player)
+                        val newPage = max(1, min(page + -1, menu.getMaxPage(player)))
 
-                        val newPage = max(1, page - 1)
+                        if (newPage == page) {
+                            return@onLeftClick
+                        }
 
-                        menu.setState(player, pageKey, newPage)
+                        menu.setState(player, Page.PAGE_KEY, newPage)
+                        menu.callEvent(player, PageChangeEvent(newPage, page))
                     }
                 }
             )
@@ -160,19 +150,30 @@ object PetsGUI {
                     ItemStackBuilder(Items.lookup(plugin.configYml.getString("gui.next-page.item")))
                         .setDisplayName(plugin.configYml.getString("gui.next-page.name"))
                         .build()
-                ) {
-                    onLeftClick { event, _, menu ->
+                )
+                {
+                    onLeftClick { event, _, _ ->
                         val player = event.whoClicked as Player
+                        val page = menu.getPage(player)
+                        val newPage = max(1, min(page + 1, menu.getMaxPage(player)))
 
-                        val pages = ceil(Pets.values()
-                            .filter { player.getPetLevel(it) > 0 }
-                            .size.toDouble() / petAreaSlots.size).toInt()
+                        if (newPage == page) {
+                            return@onLeftClick
+                        }
 
-                        val page = getPage(menu, player)
+                        menu.setState(player, Page.PAGE_KEY, newPage)
+                        menu.callEvent(player, PageChangeEvent(newPage, page))
+                    }
+                }
+            )
 
-                        val newPage = min(pages, page + 1)
-
-                        menu.setState(player, pageKey, newPage)
+            setSlot(
+                plugin.configYml.getInt("gui.pet-info.row"),
+                plugin.configYml.getInt("gui.pet-info.column"),
+                slot(petInfoItemBuilder) {
+                    onLeftClick { event, _, _ ->
+                        val player = event.whoClicked as Player
+                        player.activePet?.levelGUI?.open(player)
                     }
                 }
             )
@@ -209,6 +210,21 @@ object PetsGUI {
                     ConfigSlot(config)
                 )
             }
+
+            maxPages { player ->
+                val unlockedPets = Pets.values()
+                    .sortedByDescending { player.getPetLevel(it) }
+                    .filter { player.getPetLevel(it) > 0 }
+
+                val perPage = petAreaSlots.size
+
+                val pages = if (unlockedPets.isEmpty()) {
+                    0
+                } else {
+                    ceil((unlockedPets.size.toDouble() / perPage)).toInt()
+                }
+                pages
+            }
         }
     }