--- a/mercurial/bdiff.c
+++ b/mercurial/bdiff.c
@@ -239,7 +239,7 @@ static struct hunklist diff(struct line
static PyObject *blocks(PyObject *self, PyObject *args)
{
- PyObject *sa, *sb, *rl, *m;
+ PyObject *sa, *sb, *rl = NULL, *m;
struct line *a, *b;
struct hunklist l;
struct hunk *h;