diff --git a/message_ix/tools/add_year/__init__.py b/message_ix/tools/add_year/__init__.py
index e25f93e21..7792cc114 100644
--- a/message_ix/tools/add_year/__init__.py
+++ b/message_ix/tools/add_year/__init__.py
@@ -118,6 +118,11 @@ def add_year(sc_ref, sc_new, years_new, firstyear_new=None, lastyear_new=None,
         point for interpolation (e.g., permitting the extension of a bound to
         2025, when there is only one value in 2020).
     """
+    # TODO: when #578 is solved, remove this
+    raise NotImplementedError(
+        'This function is known to not work properly. Please see https://github.com/iiasa/message_ix/issues/578.'
+        )
+
     # III.A) Adding sets and required modifications
     years_new = sorted([x for x in years_new if str(x)
                         not in set(sc_ref.set('year'))])