@@ -597,8 +597,8 @@ class XDotParser:

     def parse(self):

         graph = pydot.graph_from_dot_data(self.xdotcode)

-        if graph.bb is None:

-            return GraphParseError()

+        if graph is None:

+            raise GraphParseError()

         xmin, ymin, xmax, ymax = map(int, graph.bb.split(","))