diff -r 20c9290a5de4 Objects/bytearrayobject.c
--- a/Objects/bytearrayobject.c	Sun Jun 21 13:57:30 2015 -0700
+++ b/Objects/bytearrayobject.c	Tue Jun 23 09:47:28 2015 +0200
@@ -2369,8 +2369,8 @@
         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;
     }
@@ -2378,7 +2378,7 @@
         return NULL;
 
     value = self->ob_bytes[where];
-    memmove(self->ob_bytes + where, self->ob_bytes + where + 1, n - where);
+    memmove(self->ob_bytes + where, self->ob_bytes + where + 1, n - where - 1);
     if (PyByteArray_Resize((PyObject *)self, n - 1) < 0)
         return NULL;
 
@@ -2409,7 +2409,7 @@
     if (!_canresize(self))
         return NULL;
 
-    memmove(self->ob_bytes + where, self->ob_bytes + where + 1, n - where);
+    memmove(self->ob_bytes + where, self->ob_bytes + where + 1, n - where - 1);
     if (PyByteArray_Resize((PyObject *)self, n - 1) < 0)
         return NULL;