diff -r ae5a4527f1fc Objects/bytearrayobject.c
--- a/Objects/bytearrayobject.c	Sun Jun 21 17:11:21 2015 +0300
+++ b/Objects/bytearrayobject.c	Tue Jun 23 10:10:46 2015 +0200
@@ -2388,8 +2388,8 @@
         return NULL;
     }
     if (where < 0)
-        where += Py_SIZE(self);
-    if (where < 0 || where >= Py_SIZE(self)) {
+        where += n;
+    if (where < 0 || where >= n) {
         PyErr_SetString(PyExc_IndexError, "pop index out of range");
         return NULL;
     }
@@ -2398,7 +2398,7 @@
 
     buf = PyByteArray_AS_STRING(self);
     value = buf[where];
-    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;
 
@@ -2430,7 +2430,7 @@
     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;