diff --git a/IPython/core/debugger.py b/IPython/core/debugger.py
index 99c83f5..2bf0764 100644
--- a/IPython/core/debugger.py
+++ b/IPython/core/debugger.py
@@ -805,9 +805,9 @@ class Pdb(OldPdb):
             new_context = int(context)
             if new_context <= 0:
                 raise ValueError()
+            self.context = new_context
         except ValueError:
             self.error("The 'context' command requires a positive integer argument.")
-        self.context = new_context
 
 
 class InterruptiblePdb(Pdb):