diff --git a/boa_engine/src/object/shape/unique_shape.rs b/boa_engine/src/object/shape/unique_shape.rs
index 0c56d80bb3e..707900ad4ef 100644
--- a/boa_engine/src/object/shape/unique_shape.rs
+++ b/boa_engine/src/object/shape/unique_shape.rs
@@ -6,7 +6,10 @@ use std::{
     rc::Rc,
 };
 
+use bitflags::bitflags;
+use boa_ast::property;
 use boa_gc::{empty_trace, Finalize, Gc, GcRefCell, Trace, WeakGc};
+use indexmap::{IndexMap, IndexSet};
 use rustc_hash::FxHashMap;
 
 use crate::{
@@ -16,44 +19,69 @@ use crate::{
 
 use super::{JsPrototype, Slot, TransitionKey};
 
+/// TODO: doc
+#[derive(Default, Debug)]
+struct Inner {
+    property_table: RefCell<IndexSet<PropertyKey>>,
+}
+
+/// TODO: doc
 #[derive(Default, Debug, Clone)]
 pub(crate) struct UniqueShape {
-    property_table: Rc<RefCell<FxHashMap<PropertyKey, u32>>>,
-    // /// Properties stored with `String`s a keys.
-    // string_properties: OrderedHashMap<JsString>,
-
-    // /// Properties stored with `Symbol`s a keys.
-    // symbol_properties: OrderedHashMap<JsSymbol>,
+    inner: Rc<Inner>,
 }
 
 impl UniqueShape {
+    /// Create shape from a pre initialized property table.
+    fn new(property_table: IndexSet<PropertyKey>) -> Self {
+        Self {
+            inner: Rc::new(Inner {
+                property_table: property_table.into(),
+            }),
+        }
+    }
+
+    /// TODO: doc
     pub(crate) fn insert_property_transition(&self, key: TransitionKey) -> Self {
         {
-            // println!("Unique: insert {}", key.property_key);
-            let mut property_table = self.property_table.borrow_mut();
-            let offset = property_table.len() as u32;
-            property_table.insert(key.property_key, offset);
+            let mut property_table = self.inner.property_table.borrow_mut();
+            let (index, inserted) = property_table.insert_full(key.property_key);
+
+            debug_assert!(inserted);
+            debug_assert!(index + 1 == property_table.len());
         }
 
         self.clone()
     }
 
+    /// TODO: doc
     pub(crate) fn remove_property_transition(&self, key: &TransitionKey) -> Self {
-        {
-            let mut property_table = self.property_table.borrow_mut();
-            property_table.remove(&key.property_key);
+        let mut property_table = self.inner.property_table.borrow_mut();
+        let Some((index, _property_key)) = property_table.shift_remove_full(&key.property_key) else {
+            return self.clone();
+        };
+
+        /// Check if it's the last property, that was deleted,
+        /// if so delete it and return self
+        if index == property_table.len() {
+            return self.clone();
         }
 
-        // self.clone()
-        todo!("implement deletion!")
+        // The property that was deleted was not the last property added.
+        // Therefore we need to create a new unique shape,
+        // to invalidateany pointers to this shape i.e inline caches.
+        let property_table = std::mem::take(&mut *property_table);
+        Self::new(property_table)
     }
 
-    #[inline]
+    /// TODO: doc
     pub(crate) fn lookup(&self, key: &PropertyKey) -> Option<Slot> {
         // println!("Unique: lookup {key}");
-        let mut property_table = self.property_table.borrow();
-        if let Some(index) = property_table.get(key) {
-            return Some(Slot { index: *index });
+        let mut property_table = self.inner.property_table.borrow();
+        if let Some(index) = property_table.get_index_of(key) {
+            return Some(Slot {
+                index: index as u32,
+            });
         }
 
         None