diff --git a/src/main/kotlin/xyz/alexcrea/cuanvil/group/AbstractMaterialGroup.kt b/src/main/kotlin/xyz/alexcrea/cuanvil/group/AbstractMaterialGroup.kt
index 937dad7..20dff07 100644
--- a/src/main/kotlin/xyz/alexcrea/cuanvil/group/AbstractMaterialGroup.kt
+++ b/src/main/kotlin/xyz/alexcrea/cuanvil/group/AbstractMaterialGroup.kt
@@ -65,7 +65,7 @@ abstract class AbstractMaterialGroup(private val name: String) {
     /**
      * Get the group contained item as a set
      */
-    abstract fun getItemTypes(): ImmutableSet<ItemType>
+    abstract fun getItemTypes(): Set<ItemType>
 
     /**
      * Get the group non-inherited items as a set
diff --git a/src/main/kotlin/xyz/alexcrea/cuanvil/group/ExcludeGroup.kt b/src/main/kotlin/xyz/alexcrea/cuanvil/group/ExcludeGroup.kt
index 1e2c1e4..6184922 100644
--- a/src/main/kotlin/xyz/alexcrea/cuanvil/group/ExcludeGroup.kt
+++ b/src/main/kotlin/xyz/alexcrea/cuanvil/group/ExcludeGroup.kt
@@ -69,8 +69,8 @@ class ExcludeGroup(name: String) : AbstractMaterialGroup(name) {
         }
     }
 
-    override fun getItemTypes(): ImmutableSet<ItemType> {
-        return Collections.unmodifiableSet(groupItems) as ImmutableSet<ItemType>
+    override fun getItemTypes(): Set<ItemType> {
+        return Collections.unmodifiableSet(groupItems)
     }
 
 
diff --git a/src/main/kotlin/xyz/alexcrea/cuanvil/group/IncludeGroup.kt b/src/main/kotlin/xyz/alexcrea/cuanvil/group/IncludeGroup.kt
index 5528ad1..9d9108e 100644
--- a/src/main/kotlin/xyz/alexcrea/cuanvil/group/IncludeGroup.kt
+++ b/src/main/kotlin/xyz/alexcrea/cuanvil/group/IncludeGroup.kt
@@ -68,8 +68,8 @@ class IncludeGroup(name: String) : AbstractMaterialGroup(name) {
         }
     }
 
-    override fun getItemTypes(): ImmutableSet<ItemType> {
-        return Collections.unmodifiableSet(groupItems) as ImmutableSet<ItemType>
+    override fun getItemTypes(): Set<ItemType> {
+        return Collections.unmodifiableSet(groupItems)
     }