diff --git a/Lib/bz2.py b/Lib/bz2.py
index 61d989bcace..fe4118f9a7a 100644
--- a/Lib/bz2.py
+++ b/Lib/bz2.py
@@ -226,7 +226,7 @@ def _read_block(self, n, return_data=True):
             data = self._buffer[self._buffer_offset : end]
             self._buffer_offset = end
             self._pos += len(data)
-            return data
+            return data if return_data else None
 
         # The loop assumes that _buffer_offset is 0. Ensure that this is true.
         self._buffer = self._buffer[self._buffer_offset:]