# HG changeset patch
# Parent 677a8e47f2c85598d588d6404c8a09f44a331544
diff --git a/src/org/python/modules/itertools/chain.java b/src/org/python/modules/itertools/chain.java
--- a/src/org/python/modules/itertools/chain.java
+++ b/src/org/python/modules/itertools/chain.java
@@ -15,16 +15,17 @@ import org.python.expose.ExposedType;
 
 import java.util.ArrayList;
 
 @ExposedType(name = "itertools.chain", base = PyObject.class)
 public class chain extends PyObject {
 
     public static final PyType TYPE = PyType.fromClass(chain.class);
     private itertools.ItertoolsIterator iter;
+    private PyObject currentIterator;
 
     @ExposedGet
     public static PyString __doc__ = new PyString(
             "chain(*iterables) --> chain object\n\nReturn a chain object "
                     + "whose .next() method returns elements from the\nfirst iterable until it is exhausted, then elements"
                     + " from the next\niterable, until all of the iterables are exhausted.");
 
     public chain() {
@@ -57,33 +58,31 @@ public class chain extends PyObject {
     final void chain___init__(final PyObject[] args, String[] kwds) {
         ArgParser ap = new ArgParser("chain", args, kwds, "iterables");
 
         //ArgParser always returns a PyTuple - I wonder why we make it pass back a PyObject?
         PyTuple tuple = (PyTuple)ap.getList(0);
         chain___init__(tuple.getArray());
     }
 
-    private void chain___init__(PyObject[] iterables) {
-        final PyObject[] iterators = new PyObject[iterables.length];
-        for (int i = 0; i < iterables.length; i++) {
-            iterators[i] = iterables[i].__iter__();
-        }
-
+    private void chain___init__(final PyObject[] iterables) {
+        currentIterator = new PyObject();
         iter = new itertools.ItertoolsIterator() {
             int iteratorIndex = 0;
 
             public PyObject __iternext__() {
                 PyObject next = null;
-                for (; iteratorIndex < iterators.length; iteratorIndex++) {
-                    next = nextElement(iterators[iteratorIndex]);
+                do {
+                    next = nextElement(currentIterator);
                     if (next != null) {
                         break;
                     }
                 }
+                while (iteratorIndex < iterables.length &&
+                       (currentIterator = iterables[iteratorIndex++].__iter__()) != null);
                 return next;
             }
 
         };
     }
 
     @ExposedMethod
     public PyObject __iter__() {