diff --git a/Tests/large_memory_test.py b/Tests/large_memory_test.py
new file mode 100644
index 000000000..148841ec2
--- /dev/null
+++ b/Tests/large_memory_test.py
@@ -0,0 +1,27 @@
+from tester import *
+
+# This test is not run automatically.
+#
+# It requires > 2gb memory for the >2 gigapixel image generated in the
+# second test.  Running this automatically would amount to a denial of
+# service on our testing infrastructure.  I expect this test to fail
+# on any 32 bit machine, as well as any smallish things (like
+# raspberrypis). It does succeed on a 3gb Ubuntu 12.04x64 VM on python
+# 2.7 an 3.2
+
+from PIL import Image
+ydim = 32769
+xdim = 48000
+f = tempfile('temp.png')
+
+def _write_png(xdim,ydim):
+    im = Image.new('L',(xdim,ydim),(0))
+    im.save(f)
+    success()
+
+def test_large():
+    """ succeeded prepatch"""
+    _write_png(xdim,ydim)
+def test_2gpx():
+    """failed prepatch"""
+    _write_png(xdim,xdim)
diff --git a/_imaging.c b/_imaging.c
index e792ebfa5..3510e1568 100644
--- a/_imaging.c
+++ b/_imaging.c
@@ -1250,6 +1250,7 @@ _putdata(ImagingObject* self, PyObject* args)
 
     image = self->image;
 
+    // UNDONE Py_ssize_t 2Gpix image issue
     n = PyObject_Length(data);
     if (n > (int) (image->xsize * image->ysize)) {
     PyErr_SetString(PyExc_TypeError, "too many data entries");
@@ -3073,7 +3074,7 @@ image_length(ImagingObject *self)
 {
     Imaging im = self->image;
 
-    return im->xsize * im->ysize;
+    return (Py_ssize_t) im->xsize * im->ysize;
 }
 
 static PyObject *