diff --git a/Lib/pdb.py b/Lib/pdb.py
index 627cd29..22dcff7 100755
--- a/Lib/pdb.py
+++ b/Lib/pdb.py
@@ -208,7 +208,9 @@
         """Custom displayhook for the exec in default(), which prevents
         assignment of the _ variable in the builtins.
         """
-        print(repr(obj))
+        # reproduce the behavior of the standard displayhook, not printing None
+        if obj is not None:
+            print(repr(obj))
 
     def default(self, line):
         if line[:1] == '!': line = line[1:]