2 files changed, 4 insertions, 0 deletions
diff --git a/gnuradio-core/src/python/gnuradio/gr/hier_block2.py b/gnuradio-core/src/python/gnuradio/gr/hier_block2.py
index 3d3545a28..b43c5feda 100644
--- a/gnuradio-core/src/python/gnuradio/gr/hier_block2.py
+++ b/gnuradio-core/src/python/gnuradio/gr/hier_block2.py
@@ -45,6 +45,8 @@ class hier_block2(object):
         """
         Pass-through member requests to the C++ object.
         """
+        if not hasattr(self, "_hb"):
+            raise RuntimeError("hier_block2: invalid state--did you forget to call gr.hier_block2.__init__ in a derived class?")
 	return getattr(self._hb, name)
 
     def connect(self, *points):
diff --git a/gnuradio-core/src/python/gnuradio/gr/top_block.py b/gnuradio-core/src/python/gnuradio/gr/top_block.py
index b9c436a0a..71e401424 100644
--- a/gnuradio-core/src/python/gnuradio/gr/top_block.py
+++ b/gnuradio-core/src/python/gnuradio/gr/top_block.py
@@ -89,6 +89,8 @@ class top_block(object):
 	self._tb = top_block_swig(name)
 
     def __getattr__(self, name):
+        if not hasattr(self, "_tb"):
+            raise RuntimeError("top_block: invalid state--did you forget to call gr.top_block.__init__ in a derived class?")
 	return getattr(self._tb, name)
 
     def start(self):