Index: src/org/python/core/PyList.java
===================================================================
--- src/org/python/core/PyList.java	(revision 6505)
+++ src/org/python/core/PyList.java	(working copy)
@@ -972,7 +972,7 @@
 
     @Override
     public synchronized int indexOf(Object o) {
-        return list.indexOf(o);
+        return list.indexOf(Py.java2py(o));
     }
 
     @Override
Index: src/org/python/core/PyTuple.java
===================================================================
--- src/org/python/core/PyTuple.java	(revision 6505)
+++ src/org/python/core/PyTuple.java	(working copy)
@@ -494,7 +494,7 @@
 
     @Override
     public int indexOf(Object o) {
-        return getList().indexOf(o);
+        return getList().indexOf(Py.java2py(o));
     }
 
     @Override
Index: tests/java/javatests/ListTest.java
===================================================================
--- tests/java/javatests/ListTest.java	(revision 6505)
+++ tests/java/javatests/ListTest.java	(working copy)
@@ -124,6 +124,7 @@
             // skip unhashable types
         }
         test_subList();
+        test_indexOf();
         test_lastIndexOf();
         test_listIterator();
         test_toArray();
@@ -243,7 +244,7 @@
     }
 
     /** Tests indexOf(Object o) */
-    public void indexOf() {
+    public void test_indexOf() {
         TestSupport.assertThat(defaultList().indexOf(3) == 3, "indexOf(3) did not return 3");
         TestSupport.assertThat(defaultList().indexOf(42) == -1,
                                "indexOf() non-existing entry did not return -1");