@@ -23,6 +23,16 @@ internal static void InitializeModuleDef()
                 module_def = ModuleDefOffset.AllocModuleDef("clr");
             }
         }
+
+        internal static void ReleaseModuleDef()
+        {
+            if (module_def == IntPtr.Zero)
+            {
+                return;
+            }
+            ModuleDefOffset.FreeModuleDef(module_def);
+            module_def = IntPtr.Zero;
+        }
 #endif
 
         /// <summary>
@@ -56,9 +66,12 @@ static void InitImport()
             // Python __import__.
             IntPtr builtins = GetNewRefToBuiltins();
             py_import = Runtime.PyObject_GetAttrString(builtins, "__import__");
+            PythonException.ThrowIfIsNull(py_import);
+
             hook = new MethodWrapper(typeof(ImportHook), "__import__", "TernaryFunc");
-            Runtime.PyObject_SetAttrString(builtins, "__import__", hook.ptr);
-            Runtime.XDecref(hook.ptr);
+            int res = Runtime.PyObject_SetAttrString(builtins, "__import__", hook.ptr);
+            PythonException.ThrowIfIsNotZero(res);
+
             Runtime.XDecref(builtins);
         }
 
@@ -69,10 +82,14 @@ static void RestoreImport()
         {
             IntPtr builtins = GetNewRefToBuiltins();
 
-            Runtime.PyObject_SetAttrString(builtins, "__import__", py_import);
+            int res = Runtime.PyObject_SetAttrString(builtins, "__import__", py_import);
+            PythonException.ThrowIfIsNotZero(res);
             Runtime.XDecref(py_import);
             py_import = IntPtr.Zero;
 
+            hook.Release();
+            hook = null;
+
             Runtime.XDecref(builtins);
         }
 
@@ -112,13 +129,26 @@ internal static void Initialize()
         /// </summary>
         internal static void Shutdown()
         {
-            if (Runtime.Py_IsInitialized() != 0)
+            if (Runtime.Py_IsInitialized() == 0)
             {
-                RestoreImport();
+                return;
+            }
 
-                Runtime.XDecref(py_clr_module);
-                Runtime.XDecref(root.pyHandle);
+            RestoreImport();
+
+            bool shouldFreeDef = Runtime.Refcount(py_clr_module) == 1;
+            Runtime.XDecref(py_clr_module);
+            py_clr_module = IntPtr.Zero;
+#if PYTHON3
+            if (shouldFreeDef)
+            {
+                ReleaseModuleDef();
             }
+#endif
+
+            Runtime.XDecref(root.pyHandle);
+            root = null;
+            CLRModule.Reset();
         }
 
         /// <summary>
 
@@ -227,7 +227,7 @@ public static IntPtr AllocModuleDef(string modulename)
             byte[] ascii = Encoding.ASCII.GetBytes(modulename);
             int size = name + ascii.Length + 1;
             IntPtr ptr = Marshal.AllocHGlobal(size);
-            for (int i = 0; i < m_free; i += IntPtr.Size)
+            for (int i = 0; i <= m_free; i += IntPtr.Size)
                 Marshal.WriteIntPtr(ptr, i, IntPtr.Zero);
             Marshal.Copy(ascii, 0, (IntPtr)(ptr + name), ascii.Length);
             Marshal.WriteIntPtr(ptr, m_name, (IntPtr)(ptr + name));
 
@@ -12,6 +12,7 @@ internal class MethodWrapper
     {
         public IntPtr mdef;
         public IntPtr ptr;
+        private bool _disposed = false;
 
         public MethodWrapper(Type type, string name, string funcType = null)
         {
@@ -31,5 +32,21 @@ public IntPtr Call(IntPtr args, IntPtr kw)
         {
             return Runtime.PyCFunction_Call(ptr, args, kw);
         }
+
+        public void Release()
+        {
+            if (_disposed)
+            {
+                return;
+            }
+            _disposed = true;
+            bool freeDef = Runtime.Refcount(ptr) == 1;
+            Runtime.XDecref(ptr);
+            if (freeDef && mdef != IntPtr.Zero)
+            {
+                Runtime.PyMem_Free(mdef);
+                mdef = IntPtr.Zero;
+            }
+        }
     }
 }
@@ -316,6 +316,11 @@ internal class CLRModule : ModuleObject
         internal static bool _SuppressDocs = false;
         internal static bool _SuppressOverloads = false;
 
+        static CLRModule()
+        {
+            Reset();
+        }
+
         public CLRModule() : base("clr")
         {
             _namespace = string.Empty;
 
@@ -187,7 +187,6 @@ internal static void Initialize(bool initSigs = false)
 
             IsFinalizing = false;
 
-            CLRModule.Reset();
             GenericUtil.Reset();
             PyScopeManager.Reset();
             ClassManager.Reset();
Original file line number	Diff line number	Diff line change
@@ -12,6 +12,7 @@ internal class MethodWrapper
12	12	{
13	13	public IntPtr mdef;
14	14	public IntPtr ptr;
	15	+ private bool _disposed = false;
15	16
16	17	public MethodWrapper(Type type, string name, string funcType = null)
17	18	{
@@ -31,5 +32,21 @@ public IntPtr Call(IntPtr args, IntPtr kw)
31	32	{
32	33	return Runtime.PyCFunction_Call(ptr, args, kw);
33	34	}
	35	+
	36	+ public void Release()
	37	+ {
	38	+ if (_disposed)
	39	+ {
	40	+ return;
	41	+ }
	42	+ _disposed = true;
	43	+ bool freeDef = Runtime.Refcount(ptr) == 1;
	44	+ Runtime.XDecref(ptr);
	45	+ if (freeDef && mdef != IntPtr.Zero)
	46	+ {
	47	+ Runtime.PyMem_Free(mdef);
	48	+ mdef = IntPtr.Zero;
	49	+ }
	50	+ }
34	51	}
35	52	}