diff --git a/dhfs-parent/server/src/main/java/com/usatiuk/dhfs/files/objects/File.java b/dhfs-parent/server/src/main/java/com/usatiuk/dhfs/files/objects/File.java
index fb63b29d..d6012ef9 100644
--- a/dhfs-parent/server/src/main/java/com/usatiuk/dhfs/files/objects/File.java
+++ b/dhfs-parent/server/src/main/java/com/usatiuk/dhfs/files/objects/File.java
@@ -5,6 +5,7 @@ import org.pcollections.PCollection;
 import org.pcollections.TreePMap;
 
 import java.util.Collection;
+import java.util.Set;
 
 public record File(JObjectKey key, PCollection<JObjectKey> refsFrom, boolean frozen,
                    long mode, long cTime, long mTime,
@@ -46,6 +47,6 @@ public record File(JObjectKey key, PCollection<JObjectKey> refsFrom, boolean fro
 
     @Override
     public Collection<JObjectKey> collectRefsTo() {
-        return chunks().values().stream().toList();
+        return Set.copyOf(chunks().values());
     }
 }
diff --git a/dhfs-parent/server/src/main/java/com/usatiuk/dhfs/objects/jkleppmanntree/structs/JKleppmannTreeNode.java b/dhfs-parent/server/src/main/java/com/usatiuk/dhfs/objects/jkleppmanntree/structs/JKleppmannTreeNode.java
index 4fda0648..890b13ea 100644
--- a/dhfs-parent/server/src/main/java/com/usatiuk/dhfs/objects/jkleppmanntree/structs/JKleppmannTreeNode.java
+++ b/dhfs-parent/server/src/main/java/com/usatiuk/dhfs/objects/jkleppmanntree/structs/JKleppmannTreeNode.java
@@ -12,6 +12,7 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.Map;
 import java.util.UUID;
+import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 // FIXME: Ideally this is two classes?
@@ -62,6 +63,6 @@ public record JKleppmannTreeNode(JObjectKey key, PCollection<JObjectKey> refsFro
                     case JKleppmannTreeNodeMetaFile file -> Stream.of(file.getFileIno());
                     default -> throw new IllegalStateException("Unexpected value: " + meta());
                 }
-        ).toList();
+        ).collect(Collectors.toUnmodifiableSet());
     }
 }