diff --git a/Libraries/LibJS/Heap/HeapBlock.cpp b/Libraries/LibJS/Heap/HeapBlock.cpp
index 0e4c9066da..8388934ae4 100644
--- a/Libraries/LibJS/Heap/HeapBlock.cpp
+++ b/Libraries/LibJS/Heap/HeapBlock.cpp
@@ -61,15 +61,16 @@ HeapBlock::HeapBlock(Heap& heap, size_t cell_size)
     : m_heap(heap)
     , m_cell_size(cell_size)
 {
-    for (size_t i = 0; i < cell_count(); ++i) {
-        auto* freelist_entry = static_cast<FreelistEntry*>(cell(i));
+    ASSERT(cell_size >= sizeof(FreelistEntry));
+
+    FreelistEntry* next = nullptr;
+    for (ssize_t i = cell_count() - 1; i >= 0; i--) {
+        auto* freelist_entry = init_freelist_entry(i);
         freelist_entry->set_live(false);
-        if (i == cell_count() - 1)
-            freelist_entry->next = nullptr;
-        else
-            freelist_entry->next = static_cast<FreelistEntry*>(cell(i + 1));
+        freelist_entry->next = next;
+        next = freelist_entry;
     }
-    m_freelist = static_cast<FreelistEntry*>(cell(0));
+    m_freelist = next;
 }
 
 Cell* HeapBlock::allocate()
@@ -84,7 +85,7 @@ void HeapBlock::deallocate(Cell* cell)
     ASSERT(cell->is_live());
     ASSERT(!cell->is_marked());
     cell->~Cell();
-    auto* freelist_entry = static_cast<FreelistEntry*>(cell);
+    auto* freelist_entry = new (cell) FreelistEntry();
     freelist_entry->set_live(false);
     freelist_entry->next = m_freelist;
     m_freelist = freelist_entry;
diff --git a/Libraries/LibJS/Heap/HeapBlock.h b/Libraries/LibJS/Heap/HeapBlock.h
index ecb1266eb6..8a12d84090 100644
--- a/Libraries/LibJS/Heap/HeapBlock.h
+++ b/Libraries/LibJS/Heap/HeapBlock.h
@@ -42,8 +42,6 @@ public:
     size_t cell_size() const { return m_cell_size; }
     size_t cell_count() const { return (block_size - sizeof(HeapBlock)) / m_cell_size; }
 
-    Cell* cell(size_t index) { return reinterpret_cast<Cell*>(&m_storage[index * cell_size()]); }
-
     Cell* allocate();
     void deallocate(Cell*);
 
@@ -72,10 +70,22 @@ public:
 private:
     HeapBlock(Heap&, size_t cell_size);
 
-    struct FreelistEntry : public Cell {
-        FreelistEntry* next;
+    struct FreelistEntry final : public Cell {
+        FreelistEntry* next { nullptr };
+
+        virtual const char* class_name() const override { return "FreelistEntry"; }
     };
 
+    Cell* cell(size_t index)
+    {
+        return reinterpret_cast<Cell*>(&m_storage[index * cell_size()]);
+    }
+
+    FreelistEntry* init_freelist_entry(size_t index)
+    {
+        return new (&m_storage[index * cell_size()]) FreelistEntry();
+    }
+
     Heap& m_heap;
     size_t m_cell_size { 0 };
     FreelistEntry* m_freelist { nullptr };