diff --git a/km3io/offline.py b/km3io/offline.py
index 25d7f181d7804f6a1e81336ab2a72fd56ff0b886..62d543390beaddbef238c71e734d89bcf24f35d9 100644
--- a/km3io/offline.py
+++ b/km3io/offline.py
@@ -134,6 +134,9 @@ class Header:
                     ", access only as dictionary key."
                 )
 
+    def __dir__(self):
+        return list(self.keys())
+
     def __str__(self):
         lines = ["MC Header:"]
         keys = set(mc_header.keys())