diff --git a/Xplat/src/main/java/vazkii/patchouli/api/PatchouliAPI.java b/Xplat/src/main/java/vazkii/patchouli/api/PatchouliAPI.java
index a20dc6bc9..4b35a136f 100644
--- a/Xplat/src/main/java/vazkii/patchouli/api/PatchouliAPI.java
+++ b/Xplat/src/main/java/vazkii/patchouli/api/PatchouliAPI.java
@@ -86,6 +86,8 @@ public interface IPatchouliAPI {
 		/**
 		 * Sends a network message to the given player
 		 * to open the book to the given entry
+		 * 
+		 * @param page Zero-indexed page number
 		 */
 		void openBookEntry(ServerPlayer player, ResourceLocation book, ResourceLocation entry, int page);
 
diff --git a/Xplat/src/main/java/vazkii/patchouli/client/base/PersistentData.java b/Xplat/src/main/java/vazkii/patchouli/client/base/PersistentData.java
index 7aab65403..8a625af9d 100644
--- a/Xplat/src/main/java/vazkii/patchouli/client/base/PersistentData.java
+++ b/Xplat/src/main/java/vazkii/patchouli/client/base/PersistentData.java
@@ -1,5 +1,7 @@
 package vazkii.patchouli.client.base;
 
+import com.google.gson.annotations.SerializedName;
+
 import net.minecraft.resources.ResourceLocation;
 
 import vazkii.patchouli.client.book.BookEntry;
@@ -57,11 +59,12 @@ public static final class BookData {
 			public static final class Bookmark {
 
 				public String entry;
-				public int page;
+				// Serialized as page for legacy reasons
+				@SerializedName("page") public int spread;
 
-				public Bookmark(String entry, int page) {
+				public Bookmark(String entry, int spread) {
 					this.entry = entry;
-					this.page = page;
+					this.spread = spread;
 				}
 
 				public BookEntry getEntry(Book book) {
diff --git a/Xplat/src/main/java/vazkii/patchouli/client/book/ClientBookRegistry.java b/Xplat/src/main/java/vazkii/patchouli/client/book/ClientBookRegistry.java
index 9351ffe34..0249f72e3 100644
--- a/Xplat/src/main/java/vazkii/patchouli/client/book/ClientBookRegistry.java
+++ b/Xplat/src/main/java/vazkii/patchouli/client/book/ClientBookRegistry.java
@@ -69,7 +69,7 @@ public void reloadLocks(boolean suppressToasts) {
 
 	/**
 	 * @param entryId Entry to force to the top of the stack
-	 * @param page    Page in the entry to force. Ignored if {@code entryId} is null.
+	 * @param page    Zero-indexed page in the entry to force. Ignored if {@code entryId} is null.
 	 */
 	public void displayBookGui(ResourceLocation bookStr, @Nullable ResourceLocation entryId, int page) {
 		Minecraft mc = Minecraft.getInstance();
diff --git a/Xplat/src/main/java/vazkii/patchouli/client/book/gui/GuiBook.java b/Xplat/src/main/java/vazkii/patchouli/client/book/gui/GuiBook.java
index 2fd271f05..f32010f04 100644
--- a/Xplat/src/main/java/vazkii/patchouli/client/book/gui/GuiBook.java
+++ b/Xplat/src/main/java/vazkii/patchouli/client/book/gui/GuiBook.java
@@ -283,7 +283,7 @@ public void handleButtonBookmark(Button button) {
 				PersistentData.save();
 				needsBookmarkUpdate = true;
 			} else {
-				displayLexiconGui(new GuiBookEntry(book, bookmark.getEntry(book), bookmark.page), true);
+				displayLexiconGui(new GuiBookEntry(book, bookmark.getEntry(book), bookmark.spread), true);
 			}
 		}
 	}
diff --git a/Xplat/src/main/java/vazkii/patchouli/client/book/gui/GuiBookEntry.java b/Xplat/src/main/java/vazkii/patchouli/client/book/gui/GuiBookEntry.java
index ab17142b3..710b53108 100644
--- a/Xplat/src/main/java/vazkii/patchouli/client/book/gui/GuiBookEntry.java
+++ b/Xplat/src/main/java/vazkii/patchouli/client/book/gui/GuiBookEntry.java
@@ -183,7 +183,7 @@ boolean isBookmarkedAlready() {
 		BookData data = PersistentData.data.getBookData(book);
 
 		for (Bookmark bookmark : data.bookmarks) {
-			if (bookmark.entry.equals(entryKey) && bookmark.page == spread) {
+			if (bookmark.entry.equals(entryKey) && bookmark.spread == spread) {
 				return true;
 			}
 		}
@@ -209,7 +209,7 @@ public static void displayOrBookmark(GuiBook currGui, BookEntry entry) {
 
 			if (gui.isBookmarkedAlready()) {
 				String key = entry.getId().toString();
-				data.bookmarks.removeIf((bm) -> bm.entry.equals(key) && bm.page == 0);
+				data.bookmarks.removeIf((bm) -> bm.entry.equals(key) && bm.spread == 0);
 				PersistentData.save();
 				currGui.needsBookmarkUpdate = true;
 				return;
diff --git a/Xplat/src/main/java/vazkii/patchouli/client/book/gui/button/GuiButtonBookBookmark.java b/Xplat/src/main/java/vazkii/patchouli/client/book/gui/button/GuiButtonBookBookmark.java
index 850b2696e..3f5436d36 100644
--- a/Xplat/src/main/java/vazkii/patchouli/client/book/gui/button/GuiButtonBookBookmark.java
+++ b/Xplat/src/main/java/vazkii/patchouli/client/book/gui/button/GuiButtonBookBookmark.java
@@ -44,7 +44,7 @@ public void renderButton(PoseStack ms, int mouseX, int mouseY, float partialTick
 			entry.getIcon().render(ms, px, py);
 
 			RenderSystem.disableDepthTest();
-			String s = Integer.toString(bookmark.page + 1);
+			String s = Integer.toString(bookmark.spread + 1);
 			if (multiblock) {
 				s = I18n.get("patchouli.gui.lexicon.visualize_letter");
 			}