diff --git a/msgpack/fallback.py b/msgpack/fallback.py
index b02e47c..5f624b8 100644
--- a/msgpack/fallback.py
+++ b/msgpack/fallback.py
@@ -529,6 +529,8 @@ class Unpacker:
                         raise ValueError("%s is not allowed for map key" % str(type(key)))
                     if isinstance(key, str):
                         key = sys.intern(key)
+                    if isinstance(key, list):
+                        key = tuple(key)
                     ret[key] = self._unpack(EX_CONSTRUCT)
                 if self._object_hook is not None:
                     ret = self._object_hook(ret)