diff --git a/Python/marshal.c b/Python/marshal.c
index a40aecc..3e106c2 100644
--- a/Python/marshal.c
+++ b/Python/marshal.c
@@ -147,7 +147,7 @@
 	else if (v == Py_True) {
 	        w_byte(TYPE_TRUE, p);
 	}
-	else if (PyLong_Check(v)) {
+	else if (PyLong_CheckExact(v)) {
 		long x = PyLong_AsLong(v);
 		if ((x == -1)  && PyErr_Occurred()) {
 			PyLongObject *ob = (PyLongObject *)v;
@@ -175,7 +175,7 @@
 			}
 		}
 	}
-	else if (PyFloat_Check(v)) {
+	else if (PyFloat_CheckExact(v)) {
 		if (p->version > 1) {
 			unsigned char buf[8];
 			if (_PyFloat_Pack8(PyFloat_AsDouble(v), 
@@ -196,7 +196,7 @@
 		}
 	}
 #ifndef WITHOUT_COMPLEX
-	else if (PyComplex_Check(v)) {
+	else if (PyComplex_CheckExact(v)) {
 		if (p->version > 1) {
 			unsigned char buf[8];
 			if (_PyFloat_Pack8(PyComplex_RealAsDouble(v),
@@ -228,7 +228,7 @@
 		}
 	}
 #endif
-	else if (PyString_Check(v)) {
+	else if (PyString_CheckExact(v)) {
 		w_byte(TYPE_STRING, p);
 		n = PyString_GET_SIZE(v);
 		if (n > INT_MAX) {
@@ -240,7 +240,7 @@
 		w_long((long)n, p);
 		w_string(PyString_AS_STRING(v), (int)n, p);
 	}
-	else if (PyUnicode_Check(v)) {
+	else if (PyUnicode_CheckExact(v)) {
 	        PyObject *utf8;
 		utf8 = PyUnicode_AsUTF8String(v);
 		if (utf8 == NULL) {
@@ -259,7 +259,7 @@
 		w_string(PyString_AS_STRING(utf8), (int)n, p);
 		Py_DECREF(utf8);
 	}
-	else if (PyTuple_Check(v)) {
+	else if (PyTuple_CheckExact(v)) {
 		w_byte(TYPE_TUPLE, p);
 		n = PyTuple_Size(v);
 		w_long((long)n, p);
@@ -267,7 +267,7 @@
 			w_object(PyTuple_GET_ITEM(v, i), p);
 		}
 	}
-	else if (PyList_Check(v)) {
+	else if (PyList_CheckExact(v)) {
 		w_byte(TYPE_LIST, p);
 		n = PyList_GET_SIZE(v);
 		w_long((long)n, p);
@@ -275,7 +275,7 @@
 			w_object(PyList_GET_ITEM(v, i), p);
 		}
 	}
-	else if (PyDict_Check(v)) {
+	else if (PyDict_CheckExact(v)) {
 		Py_ssize_t pos;
 		PyObject *key, *value;
 		w_byte(TYPE_DICT, p);
@@ -287,7 +287,7 @@
 		}
 		w_object((PyObject *)NULL, p);
 	}
-	else if (PyAnySet_Check(v)) {
+	else if (PyAnySet_CheckExact(v)) {
 		PyObject *value, *it;
 
 		if (PyObject_TypeCheck(v, &PySet_Type))