--- a/Lib/test/test_curses.py	Sat Jun 15 14:32:11 2013 -0400
+++ b/Lib/test/test_curses.py	Sat Jun 15 15:10:08 2013 -0400
@@ -252,6 +252,18 @@
     except curses.panel.error:
         pass
 
+def test_userptr_memory_leak(stdscr):
+    w = curses.newwin(10, 10)
+    p = curses.panel.new_panel(w)
+    obj = object()
+    nrefs = sys.getrefcount(obj)
+    for i in range(100):
+        p.set_userptr(obj)
+
+    p.set_userptr(None)
+    if sys.getrefcount(obj) != nrefs:
+        raise RuntimeError("set_userptr leaked references")
+
 def test_resize_term(stdscr):
     if hasattr(curses, 'resizeterm'):
         lines, cols = curses.LINES, curses.COLS
@@ -317,6 +329,7 @@
         module_funcs(stdscr)
         window_funcs(stdscr)
         test_userptr_without_set(stdscr)
+        test_userptr_memory_leak(stdscr)
         test_resize_term(stdscr)
         test_issue6243(stdscr)
         test_unget_wch(stdscr)

--- a/Misc/NEWS	Sat Jun 15 14:32:11 2013 -0400
+++ b/Misc/NEWS	Sat Jun 15 15:10:08 2013 -0400
@@ -383,6 +383,9 @@
   the default for linking if LDSHARED is not also overriden.  This restores
   Distutils behavior introduced in 3.2.3 and inadvertently dropped in 3.3.0.
 
+- Issue #18113: Fixed a refcount leak in the curses.panel module's
+  set_userptr() method.  Reported by Atsuo Ishimoto.
+
 - Implement PEP 443 "Single-dispatch generic functions".
 
 - Implement PEP 435 "Adding an Enum type to the Python standard library".

--- a/Modules/_curses_panel.c	Sat Jun 15 14:32:11 2013 -0400
+++ b/Modules/_curses_panel.c	Sat Jun 15 15:10:08 2013 -0400
@@ -322,6 +322,10 @@
 static PyObject *
 PyCursesPanel_set_panel_userptr(PyCursesPanelObject *self, PyObject *obj)
 {
+    PyObject *oldobj;
+    PyCursesInitialised;
+    oldobj = (PyObject *) panel_userptr(self->pan);
+    Py_XDECREF(oldobj);
     Py_INCREF(obj);
     return PyCursesCheckERR(set_panel_userptr(self->pan, (void*)obj),
                             "set_panel_userptr");