diff --git a/Objects/setobject.c b/Objects/setobject.c
index 0f6c902..2210edf 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -932,14 +932,31 @@
 {
 	PyObject *key, *it;
 
-	if (PyAnySet_Check(other))
+	if (PyAnySet_CheckExact(other))
 		return set_merge(so, other);
 
 	if (PyDict_CheckExact(other)) {
 		PyObject *value;
 		Py_ssize_t pos = 0;
-		while (PyDict_Next(other, &pos, &key, &value)) {
-			if (set_add_key(so, key) == -1)
+		long hash;
+		Py_ssize_t dictsize = PyDict_Size(other);
+
+		/* Do one big resize at the start, rather than
+		* incrementally resizing as we insert new keys.  Expect
+		* that there will be no (or few) overlapping keys.
+		*/
+		if (dictsize == -1)
+			return -1;
+		if ((so->fill + dictsize)*3 >= (so->mask+1)*2) {
+			if (set_table_resize(so, (so->used + dictsize)*2) != 0)
+				return -1;
+		}
+		while (_PyDict_Next(other, &pos, &key, &value, &hash)) {
+			setentry an_entry;
+
+			an_entry.hash = hash;
+			an_entry.key = key;
+			if (set_add_entry(so, &an_entry) == -1)
 				return -1;
 		}
 		return 0;
@@ -1210,7 +1227,7 @@
 	if (result == NULL)
 		return NULL;
 
-	if (PyAnySet_Check(other)) {		
+	if (PyAnySet_CheckExact(other)) {		
 		Py_ssize_t pos = 0;
 		setentry *entry;
 
@@ -1334,7 +1351,7 @@
 	if ((PyObject *)so == other)
 		return set_clear_internal(so);
 	
-	if (PyAnySet_Check(other)) {
+	if (PyAnySet_CheckExact(other)) {
 		setentry *entry;
 		Py_ssize_t pos = 0;
 
@@ -1383,7 +1400,7 @@
 	setentry *entry;
 	Py_ssize_t pos = 0;
 
-	if (!PyAnySet_Check(other)  && !PyDict_CheckExact(other)) {
+	if (!PyAnySet_CheckExact(other)  && !PyDict_CheckExact(other)) {
 		result = set_copy(so);
 		if (result == NULL)
 			return NULL;
@@ -1402,7 +1419,7 @@
 			setentry entrycopy;
 			entrycopy.hash = entry->hash;
 			entrycopy.key = entry->key;
-			if (!PyDict_Contains(other, entry->key)) {
+			if (!_PyDict_Contains(other, entry->key, entry->hash)) {
 				if (set_add_entry((PySetObject *)result, &entrycopy) == -1) {
 					Py_DECREF(result);
 					return NULL;
@@ -1473,12 +1490,10 @@
 	if (PyDict_CheckExact(other)) {
 		PyObject *value;
 		int rv;
-		while (PyDict_Next(other, &pos, &key, &value)) {
+		long hash;
+		while (_PyDict_Next(other, &pos, &key, &value, &hash)) {
 			setentry an_entry;
-			long hash = PyObject_Hash(key);
 
-			if (hash == -1)
-				return NULL;
 			an_entry.hash = hash;
 			an_entry.key = key;
 			rv = set_discard_entry(so, &an_entry);
@@ -1492,7 +1507,7 @@
 		Py_RETURN_NONE;
 	}
 
-	if (PyAnySet_Check(other)) {
+	if (PyAnySet_CheckExact(other)) {
 		Py_INCREF(other);
 		otherset = (PySetObject *)other;
 	} else {
@@ -1575,7 +1590,7 @@
 	setentry *entry;
 	Py_ssize_t pos = 0;
 
-	if (!PyAnySet_Check(other)) {
+	if (!PyAnySet_CheckExact(other)) {
 		PyObject *tmp, *result;
 		tmp = make_new_set(&PySet_Type, other);
 		if (tmp == NULL)
@@ -1604,7 +1619,7 @@
 {
 	PyObject *tmp, *result;
 
-	if (!PyAnySet_Check(other)) {
+	if (!PyAnySet_CheckExact(other)) {
 		tmp = make_new_set(&PySet_Type, other);
 		if (tmp == NULL)
 			return NULL;