diff -r a8e74448678c Objects/bytearrayobject.c
--- a/Objects/bytearrayobject.c	Tue Aug 09 15:07:06 2016 +0100
+++ b/Objects/bytearrayobject.c	Wed Aug 10 03:38:48 2016 +0900
@@ -790,33 +790,33 @@
     /* If it's not unicode, there can't be encoding or errors */
     if (encoding != NULL || errors != NULL) {
         PyErr_SetString(PyExc_TypeError,
                         "encoding or errors without a string argument");
         return -1;
     }
 
     /* Is it an int? */
-    count = PyNumber_AsSsize_t(arg, PyExc_OverflowError);
-    if (count == -1 && PyErr_Occurred()) {
-        if (PyErr_ExceptionMatches(PyExc_OverflowError))
+    if (PyIndex_Check(arg)) {
+        count = PyNumber_AsSsize_t(arg, PyExc_OverflowError);
+        if (count == -1 && PyErr_Occurred()) {
             return -1;
-        PyErr_Clear();
-    }
-    else if (count < 0) {
-        PyErr_SetString(PyExc_ValueError, "negative count");
-        return -1;
-    }
-    else {
-        if (count > 0) {
-            if (PyByteArray_Resize((PyObject *)self, count))
-                return -1;
-            memset(PyByteArray_AS_STRING(self), 0, count);
         }
-        return 0;
+        if (count < 0) {
+            PyErr_SetString(PyExc_ValueError, "negative count");
+            return -1;
+        }
+        else {
+            if (count > 0) {
+                if (PyByteArray_Resize((PyObject *)self, count))
+                    return -1;
+                memset(PyByteArray_AS_STRING(self), 0, count);
+            }
+            return 0;
+        }
     }
 
     /* Use the buffer API */
     if (PyObject_CheckBuffer(arg)) {
         Py_ssize_t size;
         Py_buffer view;
         if (PyObject_GetBuffer(arg, &view, PyBUF_FULL_RO) < 0)
             return -1;
diff -r a8e74448678c Objects/bytesobject.c
--- a/Objects/bytesobject.c	Tue Aug 09 15:07:06 2016 +0100
+++ b/Objects/bytesobject.c	Wed Aug 10 03:38:48 2016 +0900
@@ -2558,31 +2558,31 @@
         return NULL;
 
     if (PyUnicode_Check(x)) {
         PyErr_SetString(PyExc_TypeError,
                         "string argument without an encoding");
         return NULL;
     }
     /* Is it an integer? */
-    size = PyNumber_AsSsize_t(x, PyExc_OverflowError);
-    if (size == -1 && PyErr_Occurred()) {
-        if (PyErr_ExceptionMatches(PyExc_OverflowError))
+    if (PyIndex_Check(x)) {
+        size = PyNumber_AsSsize_t(x, PyExc_OverflowError);
+        if (size == -1 && PyErr_Occurred()) {
             return NULL;
-        PyErr_Clear();
-    }
-    else if (size < 0) {
-        PyErr_SetString(PyExc_ValueError, "negative count");
-        return NULL;
-    }
-    else {
-        new = _PyBytes_FromSize(size, 1);
-        if (new == NULL)
+        }
+        if (size < 0) {
+            PyErr_SetString(PyExc_ValueError, "negative count");
             return NULL;
-        return new;
+        }
+        else {
+            new = _PyBytes_FromSize(size, 1);
+            if (new == NULL)
+                return NULL;
+            return new;
+        }
     }
 
     return PyBytes_FromObject(x);
 }
 
 static PyObject*
 _PyBytes_FromBuffer(PyObject *x)
 {