diff --git a/patoolib/__init__.py b/patoolib/__init__.py
index c384c02..6acd893 100644
--- a/patoolib/__init__.py
+++ b/patoolib/__init__.py
@@ -237,7 +237,7 @@ def list_formats ():
                         print "(rar archives not supported)",
                 print
             except util.PatoolError:
-                handlers = programs.get(None, programs[command])
+                handlers = programs.get(None, programs.get(command))
                 print "   %8s: - (no program found; install one of %s)" % \
                       (command, ", ".join(handlers))
     return 0