diff --git a/_py/code/_assertionnew.py b/_py/code/_assertionnew.py
index 606dfa75c..21ed1ab23 100644
--- a/_py/code/_assertionnew.py
+++ b/_py/code/_assertionnew.py
@@ -10,6 +10,29 @@ import py
 from _py.code.assertion import _format_explanation, BuiltinAssertionError
 
 
+if sys.platform.startswith("java") and sys.version_info < (2, 5, 2):
+    # See http://bugs.jython.org/issue1497
+    _exprs = ("BoolOp", "BinOp", "UnaryOp", "Lambda", "IfExp", "Dict",
+              "ListComp", "GeneratorExp", "Yield", "Compare", "Call",
+              "Repr", "Num", "Str", "Attribute", "Subscript", "Name",
+              "List", "Tuple")
+    _stmts = ("FunctionDef", "ClassDef", "Return", "Delete", "Assign",
+              "AugAssign", "Print", "For", "While", "If", "With", "Raise",
+              "TryExcept", "TryFinally", "Assert", "Import", "ImportFrom",
+              "Exec", "Global", "Expr", "Pass", "Break", "Continue")
+    _expr_nodes = set(getattr(ast, name) for name in _exprs)
+    _stmt_nodes = set(getattr(ast, name) for name in _stmts)
+    def _is_ast_expr(node):
+        return node.__class__ in _expr_nodes
+    def _is_ast_stmt(node):
+        return node.__class__ in _stmt_nodes
+else:
+    def _is_ast_expr(node):
+        return isinstance(node, ast.expr)
+    def _is_ast_stmt(node):
+        return isinstance(node, ast.stmt)
+
+
 class Failure(Exception):
     """Error found while interpreting AST."""
 
@@ -91,7 +114,7 @@ class DebugInterpreter(ast.NodeVisitor):
 
     def generic_visit(self, node):
         # Fallback when we don't have a special implementation.
-        if isinstance(node, ast.expr):
+        if _is_ast_expr(node):
             mod = ast.Expression(node)
             co = self._compile(mod)
             try:
@@ -100,7 +123,7 @@ class DebugInterpreter(ast.NodeVisitor):
                 raise Failure()
             explanation = self.frame.repr(result)
             return explanation, result
-        elif isinstance(node, ast.stmt):
+        elif _is_ast_stmt(node):
             mod = ast.Module([node])
             co = self._compile(mod, "exec")
             try: