diff --git a/swh/model/collections.py b/swh/model/collections.py
index 38d28a3..5fd8f68 100644
--- a/swh/model/collections.py
+++ b/swh/model/collections.py
@@ -1,59 +1,62 @@
 # Copyright (C) 2020 The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 from collections.abc import Mapping
 from typing import Dict, Generic, Iterable, Optional, Tuple, TypeVar, Union
 
 KT = TypeVar("KT")
 VT = TypeVar("VT")
 
 
 class ImmutableDict(Mapping, Generic[KT, VT]):
     data: Tuple[Tuple[KT, VT], ...]
 
     def __init__(
         self,
         data: Union[
             Iterable[Tuple[KT, VT]], "ImmutableDict[KT, VT]", Dict[KT, VT]
         ] = {},
     ):
         if isinstance(data, dict):
             self.data = tuple(item for item in data.items())
         elif isinstance(data, ImmutableDict):
             self.data = data.data
         else:
             self.data = tuple(data)
 
+    def __repr__(self):
+        return f"ImmutableDict({dict(self.data)!r})"
+
     def __getitem__(self, key):
         for (k, v) in self.data:
             if k == key:
                 return v
         raise KeyError(key)
 
     def __iter__(self):
         for (k, v) in self.data:
             yield k
 
     def __len__(self):
         return len(self.data)
 
     def items(self):
         yield from self.data
 
     def __hash__(self):
         return hash(tuple(sorted(self.data)))
 
     def copy_pop(self, popped_key) -> Tuple[Optional[VT], "ImmutableDict[KT, VT]"]:
         """Returns a copy of this ImmutableDict without the given key,
         as well as the value associated to the key."""
         popped_value = None
         new_items = []
         for (key, value) in self.data:
             if key == popped_key:
                 popped_value = value
             else:
                 new_items.append((key, value))
 
         return (popped_value, ImmutableDict(new_items))