diff -r 42bf74b90626 Include/object.h
--- a/Include/object.h	Wed Mar 20 14:26:33 2013 -0700
+++ b/Include/object.h	Sat Mar 30 22:04:11 2013 -0700
@@ -809,6 +809,8 @@
  * Python integers aren't currently weakly referencable.  Best practice is
  * to use Py_CLEAR() even if you can't think of a reason for why you need to.
  */
+
+
 #define Py_CLEAR(op)                            \
     do {                                        \
         if (op) {                               \
@@ -819,8 +821,19 @@
     } while (0)
 
 /* Macros to use in case the object pointer may be NULL: */
-#define Py_XINCREF(op) do { if ((op) == NULL) ; else Py_INCREF(op); } while (0)
-#define Py_XDECREF(op) do { if ((op) == NULL) ; else Py_DECREF(op); } while (0)
+#define Py_XINCREF(op)                             \
+    do {                                           \
+        PyObject* _py_tmp=(PyObject*)(op);         \
+        if (_py_tmp != NULL)                       \
+            Py_INCREF(_py_tmp);                    \
+    } while (0)                                    
+
+#define Py_XDECREF(op)                             \
+    do {                                           \
+        PyObject* _py_tmp=(PyObject*)(op);         \
+        if (_py_tmp != NULL)                       \
+            Py_DECREF(_py_tmp);                    \
+    } while (0)
 
 /*
 These are provided as conveniences to Python runtime embedders, so that
diff -r 42bf74b90626 Misc/ACKS
--- a/Misc/ACKS	Wed Mar 20 14:26:33 2013 -0700
+++ b/Misc/ACKS	Sat Mar 30 22:04:11 2013 -0700
@@ -964,6 +964,7 @@
 Remi Pointel
 Ariel Poliak
 Guilherme Polo
+Illia Polosukhin
 Michael Pomraning
 Iustin Pop
 Claudiu Popa
diff -r 42bf74b90626 Misc/NEWS
--- a/Misc/NEWS	Wed Mar 20 14:26:33 2013 -0700
+++ b/Misc/NEWS	Sat Mar 30 22:04:11 2013 -0700
@@ -19,6 +19,9 @@
   and kwarg and kwargannotation. Change the column offset of ast.Attribute to be
   at the attribute name.
 
+- Issue #17206: Py_XDECREF() and Py_XINCREF() now expands their arguments once 
+  instead of multiple times. Patch written by Illia Polosukhin.
+
 - Issue #17434: Properly raise a SyntaxError when a string occurs between future
   imports.
 
diff -r 42bf74b90626 Modules/_testcapimodule.c
--- a/Modules/_testcapimodule.c	Wed Mar 20 14:26:33 2013 -0700
+++ b/Modules/_testcapimodule.c	Sat Mar 30 22:04:11 2013 -0700
@@ -2468,6 +2468,17 @@
     return Py_BuildValue("Nl", _PyLong_FromTime_t(sec), nsec);
 }
 
+static void
+test_xdecref_doesnt_leak(PyObject* ob)
+{
+    Py_XDECREF(PyLong_FromLong(0));
+}
+
+static void
+test_decref_doesnt_leak(PyObject* ob)
+{
+    Py_DECREF(PyLong_FromLong(0));
+}
 
 static PyMethodDef TestMethods[] = {
     {"raise_exception",         raise_exception,                 METH_VARARGS},
@@ -2478,6 +2489,8 @@
     {"test_dict_iteration",     (PyCFunction)test_dict_iteration,METH_NOARGS},
     {"test_lazy_hash_inheritance",      (PyCFunction)test_lazy_hash_inheritance,METH_NOARGS},
     {"test_long_api",           (PyCFunction)test_long_api,      METH_NOARGS},
+    {"test_xdecref_doesnt_leak",           (PyCFunction)test_xdecref_doesnt_leak,      METH_NOARGS},
+    {"test_decref_doesnt_leak",           (PyCFunction)test_decref_doesnt_leak,      METH_NOARGS},
     {"test_long_and_overflow", (PyCFunction)test_long_and_overflow,
      METH_NOARGS},
     {"test_long_as_double",     (PyCFunction)test_long_as_double,METH_NOARGS},