diff -r 2344e8b7a8aa Objects/bytearrayobject.c
--- a/Objects/bytearrayobject.c	Sun Jun 21 17:12:16 2015 +0300
+++ b/Objects/bytearrayobject.c	Tue Jun 23 10:13:14 2015 +0200
@@ -2527,8 +2527,8 @@
         return NULL;
     }
     if (index < 0)
-        index += Py_SIZE(self);
-    if (index < 0 || index >= Py_SIZE(self)) {
+        index += n;
+    if (index < 0 || index >= n) {
         PyErr_SetString(PyExc_IndexError, "pop index out of range");
         return NULL;
     }
@@ -2537,7 +2537,7 @@
 
     buf = PyByteArray_AS_STRING(self);
     value = buf[index];
-    memmove(buf + index, buf + index + 1, n - index);
+    memmove(buf + index, buf + index + 1, n - index - 1);
     if (PyByteArray_Resize((PyObject *)self, n - 1) < 0)
         return NULL;
 
@@ -2573,7 +2573,7 @@
     if (!_canresize(self))
         return NULL;
 
-    memmove(buf + where, buf + where + 1, n - where);
+    memmove(buf + where, buf + where + 1, n - where - 1);
     if (PyByteArray_Resize((PyObject *)self, n - 1) < 0)
         return NULL;