diff --git a/loader/src/main/java/net/neoforged/fml/ModList.java b/loader/src/main/java/net/neoforged/fml/ModList.java
index 8c309a34e..9de555ba9 100644
--- a/loader/src/main/java/net/neoforged/fml/ModList.java
+++ b/loader/src/main/java/net/neoforged/fml/ModList.java
@@ -9,6 +9,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.Locale;
@@ -46,9 +47,9 @@ public class ModList {
     private List<ModContainer> sortedContainers;
 
     private ModList(final List<ModFile> modFiles, final List<ModInfo> sortedList) {
-        this.modFiles = modFiles.stream().map(ModFile::getModFileInfo).map(ModFileInfo.class::cast).collect(Collectors.toList());
-        this.sortedList = sortedList.stream().map(ModInfo.class::cast).collect(Collectors.toList());
-        this.fileById = this.modFiles.stream().map(IModFileInfo::getMods).flatMap(Collection::stream).map(ModInfo.class::cast).collect(Collectors.toMap(ModInfo::getModId, ModInfo::getOwningFile));
+        this.modFiles = modFiles.stream().map(ModFile::getModFileInfo).toList();
+        this.sortedList = sortedList.stream().map(IModInfo.class::cast).toList();
+        this.fileById = Collections.unmodifiableMap(this.modFiles.stream().map(IModFileInfo::getMods).flatMap(Collection::stream).map(ModInfo.class::cast).collect(Collectors.toMap(ModInfo::getModId, ModInfo::getOwningFile)));
         CrashReportCallables.registerCrashCallable("Mod List", this::crashReport);
     }