diff --git a/src/ep_bitmap.c b/src/ep_bitmap.c
index dfeef62..5eac856 100755
--- a/src/ep_bitmap.c
+++ b/src/ep_bitmap.c
@@ -44,7 +44,7 @@ static int bitmap_init(BitmapObject *self, PyObject *args, PyObject *kwds)
   const char *stock;
   int width = 0, height = 0;
   
-  if (!PyArg_ParseTupleAndKeywords(args, kwds, "$sii", kwlist, &stock, &width, &height))
+  if (!PyArg_ParseTupleAndKeywords(args, kwds, "|$sii", kwlist, &stock, &width, &height))
     return -1;
   
   if (stock)