@@ -236,10 +236,10 @@ private void Dispose(bool disposing)
 
         ~PyBuffer()
         {
-            if (disposedValue)
-            {
-                return;
-            }
+            Debug.Assert(!disposedValue);
+
+            _exporter.CheckRun();
+            
             Finalizer.Instance.AddFinalizedObject(ref _view.obj);
         }
 
 
@@ -27,6 +27,7 @@ public partial class PyObject : DynamicObject, IDisposable
 #endif  
 
         protected internal IntPtr obj = IntPtr.Zero;
+        readonly int run = Runtime.GetRun();
 
         public static PyObject None => new PyObject(new BorrowedReference(Runtime.PyNone));
         internal BorrowedReference Reference => new BorrowedReference(this.obj);
@@ -95,11 +96,15 @@ internal PyObject(in StolenReference reference)
         // when the managed wrapper is garbage-collected.
         ~PyObject()
         {
-            if (obj == IntPtr.Zero)
-            {
-                return;
-            }
+            Debug.Assert(obj != IntPtr.Zero);
+
+#if TRACE_ALLOC
+            CheckRun();
+#endif
+
             Finalizer.Instance.AddFinalizedObject(ref obj);
+
+            Dispose(false);
         }
 
 
@@ -167,17 +172,6 @@ public object AsManagedObject(Type t)
 
         internal bool IsDisposed => obj == IntPtr.Zero;
 
-        /// <summary>
-        /// Dispose Method
-        /// </summary>
-        /// <remarks>
-        /// The Dispose method provides a way to explicitly release the
-        /// Python object represented by a PyObject instance. It is a good
-        /// idea to call Dispose on PyObjects that wrap resources that are
-        /// limited or need strict lifetime control. Otherwise, references
-        /// to Python objects will not be released until a managed garbage
-        /// collection occurs.
-        /// </remarks>
         protected virtual void Dispose(bool disposing)
         {
             if (this.obj == IntPtr.Zero)
@@ -188,6 +182,8 @@ protected virtual void Dispose(bool disposing)
             if (Runtime.Py_IsInitialized() == 0)
                 throw new InvalidOperationException("Python runtime must be initialized");
 
+            CheckRun();
+
             if (!Runtime.IsFinalizing)
             {
                 long refcount = Runtime.Refcount(this.obj);
@@ -221,10 +217,26 @@ protected virtual void Dispose(bool disposing)
             this.obj = IntPtr.Zero;
         }
 
+        /// <summary>
+        /// The Dispose method provides a way to explicitly release the
+        /// Python object represented by a PyObject instance. It is a good
+        /// idea to call Dispose on PyObjects that wrap resources that are
+        /// limited or need strict lifetime control. Otherwise, references
+        /// to Python objects will not be released until a managed garbage
+        /// collection occurs.
+        /// </summary>
         public void Dispose()
         {
-            Dispose(true);
             GC.SuppressFinalize(this);
+            Dispose(true);
+        }
+
+        internal void CheckRun()
+        {
+            if (run != Runtime.GetRun())
+                throw new InvalidOperationException(
+                    "PythonEngine was shut down after this object was created." +
+                    " It is an error to attempt to dispose or to continue using it.");
         }
 
         internal BorrowedReference GetPythonTypeReference()
 
@@ -85,7 +85,15 @@ internal static Version PyVersion
             }
         }
 
-        /// <summary>
+        static int run = 0;
+
+        internal static int GetRun()
+        {
+            int runNumber = run;
+            Debug.Assert(runNumber > 0, "This must only be called after Runtime is initialized at least once");
+            return runNumber;
+        }
+
         /// Initialize the runtime...
         /// </summary>
         /// <remarks>Always call this method from the Main thread.  After the
@@ -110,6 +118,9 @@ internal static void Initialize(bool initSigs = false, ShutdownMode mode = Shutd
             if (!interpreterAlreadyInitialized)
             {
                 Py_InitializeEx(initSigs ? 1 : 0);
+
+                NewRun();
+
                 if (PyEval_ThreadsInitialized() == 0)
                 {
                     PyEval_InitThreads();
@@ -130,6 +141,16 @@ internal static void Initialize(bool initSigs = false, ShutdownMode mode = Shutd
                 {
                     PyGILState_Ensure();
                 }
+
+                BorrowedReference pyRun = PySys_GetObject("__pynet_run__");
+                if (pyRun != null)
+                {
+                    run = checked((int)PyLong_AsSignedSize_t(pyRun));
+                }
+                else
+                {
+                    NewRun();
+                }
             }
             MainManagedThreadId = Thread.CurrentThread.ManagedThreadId;
 
@@ -175,6 +196,13 @@ internal static void Initialize(bool initSigs = false, ShutdownMode mode = Shutd
             inspect = GetModuleLazy("inspect");
         }
 
+        static void NewRun()
+        {
+            run++;
+            using var pyRun = PyLong_FromLongLong(run);
+            PySys_SetObject("__pynet_run__", pyRun);
+        }
+
         private static void InitPyMembers()
         {
             IntPtr op;
Original file line number	Diff line number	Diff line change
@@ -236,10 +236,10 @@ private void Dispose(bool disposing)
236	236
237	237	~PyBuffer()
238	238	{
239		- if (disposedValue)
240		- {
241		- return;
242		- }
	239	+ Debug.Assert(!disposedValue);
	240	+
	241	+ _exporter.CheckRun();
	242	+
243	243	Finalizer.Instance.AddFinalizedObject(ref _view.obj);
244	244	}
245	245