diff --git a/src/main/java/org/embeddedt/modernfix/mixin/perf/patchouli_deduplicate_books/ClientBookRegistryMixin.java b/src/main/java/org/embeddedt/modernfix/mixin/perf/patchouli_deduplicate_books/ClientBookRegistryMixin.java
index f31a628f..4bdced31 100644
--- a/src/main/java/org/embeddedt/modernfix/mixin/perf/patchouli_deduplicate_books/ClientBookRegistryMixin.java
+++ b/src/main/java/org/embeddedt/modernfix/mixin/perf/patchouli_deduplicate_books/ClientBookRegistryMixin.java
@@ -8,6 +8,7 @@ import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.injection.At;
 import org.spongepowered.asm.mixin.injection.Inject;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+import vazkii.patchouli.client.book.BookContents;
 import vazkii.patchouli.client.book.BookEntry;
 import vazkii.patchouli.client.book.BookPage;
 import vazkii.patchouli.client.book.ClientBookRegistry;
@@ -26,32 +27,41 @@ public class ClientBookRegistryMixin {
     @Inject(method = "reload", at = @At("RETURN"), remap = false)
     private void performDeduplication(CallbackInfo ci) {
         Field templateField = ObfuscationReflectionHelper.findField(PageTemplate.class, "template");
+        Field contentsField = ObfuscationReflectionHelper.findField(Book.class, "contents");
         Field componentsField = ObfuscationReflectionHelper.findField(BookTemplate.class, "components");
         Field itemsField = ObfuscationReflectionHelper.findField(ComponentItemStack.class, "items");
         int numItemsCleared = 0;
         for(Book book : BookRegistry.INSTANCE.books.values()) {
-            for(BookEntry entry : book.contents.entries.values()) {
-                for(BookPage page : entry.getPages()) {
-                    if(page instanceof PageTemplate) {
-                        List<TemplateComponent> components;
-                        try {
-                            BookTemplate template = (BookTemplate)templateField.get(page);
-                            components = (List<TemplateComponent>)componentsField.get(template);
-                            for(TemplateComponent component : components) {
-                                if(component instanceof ComponentItemStack) {
-                                    ItemStack[] items = (ItemStack[])itemsField.get(component);
-                                    for(int i = 0; i < items.length; i++) {
-                                        if(items[i] != null && items[i].getItem() == Items.AIR) {
+            try {
+                BookContents contents = (BookContents)contentsField.get(book);
+                if(contents == null || contents.entries == null)
+                    continue;
+                for(BookEntry entry : contents.entries.values()) {
+                    for(BookPage page : entry.getPages()) {
+                        if(page instanceof PageTemplate) {
+                            List<TemplateComponent> components;
+                            BookTemplate template = (BookTemplate) templateField.get(page);
+                            if(template == null)
+                                continue;
+                            components = (List<TemplateComponent>) componentsField.get(template);
+                            if(components == null)
+                                continue;
+                            for (TemplateComponent component : components) {
+                                if (component instanceof ComponentItemStack) {
+                                    ItemStack[] items = (ItemStack[]) itemsField.get(component);
+                                    if(items == null)
+                                        continue;
+                                    for (int i = 0; i < items.length; i++) {
+                                        if (items[i] != null && items[i].getItem() == Items.AIR) {
                                             items[i] = ItemStack.EMPTY;
                                         }
                                     }
                                 }
                             }
-                        } catch(ReflectiveOperationException e) {
-                            continue;
                         }
                     }
                 }
+            } catch(ReflectiveOperationException ignored) {
             }
         }
         ModernFix.LOGGER.info("Cleared {} unneeded book NBT tags", numItemsCleared);