diff --git a/src/if_py_both.h b/src/if_py_both.h
index dd7e82a..7c205f8 100644
--- a/src/if_py_both.h
+++ b/src/if_py_both.h
@@ -2368,7 +2368,7 @@
     PyInt	numreplaced = 0;
     PyInt	numadded = 0;
     PyInt	size;
-    listitem_T	**lis;
+    listitem_T	**lis = NULL;
 
     size = ListLength(self);
 
@@ -2503,8 +2503,8 @@
 	{
 	    Py_DECREF(iterator);
 	    PyErr_FORMAT(PyExc_ValueError,
-		    N_("attempt to assign sequence of size greater then %d "
-			"to extended slice"), slicelen);
+		    N_("attempt to assign sequence of size greater then %ld "
+			"to extended slice"), (long)slicelen);
 	    list_restore(numadded, numreplaced, slicelen, l, lis, lastaddedli);
 	    PyMem_Free(lis);
 	    return -1;
@@ -2516,8 +2516,8 @@
     if (step != 1 && i != slicelen)
     {
 	PyErr_FORMAT2(PyExc_ValueError,
-		N_("attempt to assign sequence of size %d to extended slice "
-		    "of size %d"), i, slicelen);
+		N_("attempt to assign sequence of size %ld to extended slice "
+		    "of size %ld"), (long)i, (long)slicelen);
 	list_restore(numadded, numreplaced, slicelen, l, lis, lastaddedli);
 	PyMem_Free(lis);
 	return -1;