diff --git a/benchs/bench_fw/index.py b/benchs/bench_fw/index.py
index 527eb29c06..745235cd54 100644
--- a/benchs/bench_fw/index.py
+++ b/benchs/bench_fw/index.py
@@ -73,7 +73,10 @@ def set_index_param_dict(index, param_dict, assert_same=False):
     def set_index_param(index, name, val, assert_same=False):
         index = faiss.downcast_index(index)
         val = int(val)
-        if isinstance(index, faiss.IndexPreTransform):
+        if (
+            isinstance(index, faiss.IndexPreTransform)
+            or isinstance(index, faiss.IndexIDMap)
+        ):
             Index.set_index_param(index.index, name, val)
             return
         elif name == "snap":