diff --git a/Lib/pdb.py b/Lib/pdb.py
index e272f2ebb32..627cd29ba7b 100755
--- a/Lib/pdb.py
+++ b/Lib/pdb.py
@@ -841,8 +841,7 @@ class Pdb(bdb.Bdb, cmd.Cmd):
     def do_alias(self, arg):
         args = arg.split()
         if len(args) == 0:
-            keys = self.aliases.keys()
-            keys.sort()
+            keys = sorted(self.aliases.keys())
             for alias in keys:
                 print("%s = %s" % (alias, self.aliases[alias]), file=self.stdout)
             return
diff --git a/Misc/NEWS b/Misc/NEWS
index 54dcbca79ef..fe856ae83d0 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -70,6 +70,8 @@ C-API
 Library
 -------
 
+- Issue #6888: pdb's alias command was broken when no arguments were given.
+
 - Issue #6857: Default format() alignment should be '>' for Decimal
   instances.