diff --git a/SharedPtr.hpp b/SharedPtr.hpp
index 82bb20c..d119ae6 100644
--- a/SharedPtr.hpp
+++ b/SharedPtr.hpp
@@ -1,6 +1,8 @@
 #include <atomic>
+#include <type_traits>
 #ifndef _POWELLCS440
 #include <cassert>
+#include <concepts>
 #include <iostream>
 
 #define todo(msg)                                                              \
@@ -9,75 +11,65 @@
 
 namespace cs440 {
 using counter = std::atomic<std::size_t>;
-template <typename T> class SharedPtr;
-class Key {
-  Key() {}
+template <typename T> struct Base {
+  template <typename U> friend struct Base;
+
+  T *ptr;
+  Base(T *ptr) : ptr{ptr} {}
+  template <typename U> Base(Base<U> const &ptr) : ptr{ptr.ptr} {}
+  template <typename U> operator U() { return U(*this); }
 
 public:
-  template <typename U> friend class SharedPtr;
-  template <typename U> void increment(SharedPtr<U> const &ptr) {
-    const_cast<std::atomic<size_t> &>(*ptr.count)++;
-  }
-  template <typename U> counter *get_counter(SharedPtr<U> const &ptr) {
-    return const_cast<std::atomic<size_t> *>(ptr.count);
-  }
-  template <typename U> U *get_ptr(SharedPtr<U> const &ptr) {
-    return const_cast<U *>(ptr.ptr);
-  }
-  template <typename U> void nullify(SharedPtr<U> &&ptr) {
-    ptr.ptr = nullptr;
-    ptr.count = nullptr;
-  }
+  virtual T &operator*() { return *ptr; }
+  virtual T *operator->() { return ptr; }
+  virtual ~Base() = default;
+};
+template <typename T, typename U> class Derived : public Base<T> {
+  static_assert(std::is_base_of_v<T, U>);
+  U *ptr;
+
+public:
+  Derived(Base<T> b) : Derived{*dynamic_cast<Derived<T, U> *>(&b)} {}
+  U &operator*() { return *ptr; }
+  U *operator->() { return ptr; }
+  virtual ~Derived() { delete this->ptr; }
 };
 template <typename T> class SharedPtr {
-  T *ptr;
-  std::atomic<std::size_t> *count;
-
 public:
-  friend class Key;
-  SharedPtr() : ptr{nullptr}, count{new std::atomic<std::size_t>{1}} {}
+  Base<T> *ptr;
+  counter *count;
+
+  // problem?
+  SharedPtr() : ptr{nullptr}, count{new std::atomic<std::size_t>{0}} {}
   template <typename U>
   explicit SharedPtr(U *ptr)
-      : ptr{ptr}, count{new std::atomic<std::size_t>{1}} {}
-  SharedPtr(const SharedPtr &p) : ptr{p.ptr} {
-    Key().increment(p);
-    this->count = Key().get_counter(p);
-  }
+      : ptr{static_cast<Base<T> *>(new Derived<T, U>{ptr})},
+        count{new std::atomic<std::size_t>{ptr ? 1 : 0}} {}
+  SharedPtr(const SharedPtr &p) : ptr{p.ptr} {}
   template <typename U>
-  SharedPtr(const SharedPtr<U> &p) : ptr{Key().get_ptr(p)} {
-    Key().increment(p);
-    this->count = Key().get_counter(p);
+  SharedPtr(const SharedPtr<U> &p) : ptr(Base<T>(*p.ptr)), count{p.count} {
+    (*count)++;
   }
-  SharedPtr(SharedPtr &&p)
-      : count{Key().get_counter(p)}, ptr{Key().get_ptr(p)} {
-    Key().nullify(p);
-  }
-  template <typename U>
-  SharedPtr(SharedPtr<U> &&p)
-      : count{Key().get_counter(p)}, ptr{Key().get_ptr(p)} {
-    Key().nullify(p);
+  SharedPtr(SharedPtr &&p) : ptr{p.ptr} { p.ptr = nullptr; }
+  template <typename U> SharedPtr(SharedPtr<U> &&p) : ptr{p.ptr} {
+    p.ptr = nullptr;
   }
   SharedPtr &operator=(const SharedPtr &ptr) {
-    Key().increment(ptr);
-    this->count = Key().get_counter(ptr);
-    this->ptr = Key().get_ptr(ptr);
+    this->ptr = ptr.ptr;
+    (*count)++;
     return *this;
   }
   template <typename U> SharedPtr<T> &operator=(const SharedPtr<U> &ptr) {
-    Key().increment(ptr);
-    this->count = Key().get_counter(ptr);
-    this->ptr = Key().get_ptr(ptr);
+    this->ptr = new Derived<T, U>{Base<T>(ptr.ptr)};
     return *this;
   }
   SharedPtr &operator=(SharedPtr &&p) {
-    this->count = Key().get_counter(ptr);
-    this->ptr = Key().get_ptr(ptr);
-    Key().nullify(p);
+    ptr = p.ptr;
+    p.ptr = nullptr;
   }
   template <typename U> SharedPtr &operator=(SharedPtr<U> &&p) {
-    this->count = Key().get_counter(ptr);
-    this->ptr = Key().get_ptr(ptr);
-    Key().nullify(p);
+    ptr = p.ptr;
+    p.ptr = nullptr;
   }
   ~SharedPtr() {
     if (this->count == nullptr) {
@@ -91,33 +83,18 @@ public:
       delete this->ptr;
     }
   }
-  void reset() {
-    if (this->count != nullptr) {
-      if (--(*this->count) == 0) {
-        delete this->count;
-        delete this->ptr;
-        return;
-      }
-    }
-    this->ptr = nullptr;
-    this->count = nullptr;
-  }
-  template <typename U> void reset(U *p) {
-    this->reset();
-    this->count = new counter{1};
-    this->ptr = p;
-  }
-  T *get() const { return this->ptr; }
-  T &operator*() const { return *this->ptr; }
-  T *operator->() const { return this->ptr; }
-  explicit operator bool() const { return this->ptr != nullptr; }
-  template <typename T1, typename T2>
+  void reset() { this->ptr = nullptr; }
+  template <typename U> void reset(U *p) { this->ptr = new Derived<U>{p}; }
+  T *get() const { return this->ptr->ptr; }
+  T &operator*() const { return this->ptr->operator*(); }
+  T *operator->() const { return this->ptr->operator->(); }
+  explicit operator bool() const { return this->ptr->ptr != nullptr; }
   template <typename U>
-  friend SharedPtr<T> static_pointer_cast(const SharedPtr<U> &sp) {
+  friend SharedPtr<U> static_pointer_cast(const SharedPtr<T> &sp) {
     todo("");
   }
   template <typename U>
-  friend SharedPtr<T> dynamic_pointer_cast(const SharedPtr<U> &sp) {
+  friend SharedPtr<U> dynamic_pointer_cast(const SharedPtr<T> &sp) {
     todo("");
   }
 };