diff --git a/src/main/java/de/studiocode/invui/item/Item.java b/src/main/java/de/studiocode/invui/item/Item.java
index 8175d89..d48f6d5 100644
--- a/src/main/java/de/studiocode/invui/item/Item.java
+++ b/src/main/java/de/studiocode/invui/item/Item.java
@@ -36,9 +36,11 @@ public interface Item {
     void removeWindow(Window window);
     
     /**
-     * Gets all the {@link Window}s the {@link Item} is displayed in.
+     * Gets an immutable {@link Set} of all the {@link Window}s where this
+     * {@link Item} is displayed in.
      *
-     * @return The {@link Set} of {@link Window}s the {@link Item} is displayed in.
+     * @return An immutable view of the {@link Set} of all the {@link Window}s
+     * where this {@link Item} is displayed in.
      */
     Set<Window> getWindows();
     
diff --git a/src/main/java/de/studiocode/invui/item/impl/BaseItem.java b/src/main/java/de/studiocode/invui/item/impl/BaseItem.java
index 1e6631a..833b350 100644
--- a/src/main/java/de/studiocode/invui/item/impl/BaseItem.java
+++ b/src/main/java/de/studiocode/invui/item/impl/BaseItem.java
@@ -3,6 +3,7 @@ package de.studiocode.invui.item.impl;
 import de.studiocode.invui.item.Item;
 import de.studiocode.invui.window.Window;
 
+import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
 
@@ -25,7 +26,7 @@ public abstract class BaseItem implements Item {
     
     @Override
     public Set<Window> getWindows() {
-        return windows;
+        return Collections.unmodifiableSet(windows);
     }
     
     @Override
diff --git a/src/main/java/de/studiocode/invui/virtualinventory/VirtualInventory.java b/src/main/java/de/studiocode/invui/virtualinventory/VirtualInventory.java
index a3042c8..1ea9a98 100644
--- a/src/main/java/de/studiocode/invui/virtualinventory/VirtualInventory.java
+++ b/src/main/java/de/studiocode/invui/virtualinventory/VirtualInventory.java
@@ -550,6 +550,16 @@ public class VirtualInventory implements ConfigurationSerializable {
         windows.remove(window);
     }
     
+    /**
+     * Gets an immutable view of the {@link Set} that contains all the {@link Window}s that
+     * display this {@link VirtualInventory}.
+     * 
+     * @return An UnmodifiableSet of all the {@link Window}s that show this {@link VirtualInventory}.
+     */
+    public Set<Window> getWindows() {
+        return Collections.unmodifiableSet(windows);
+    }
+    
     /**
      * Notifies all {@link Window}s displaying this {@link VirtualInventory} to update their
      * representative {@link ItemStack}s.