diff --git a/src/unitxt/metrics.py b/src/unitxt/metrics.py
index c1fc647f21..a0052c6500 100644
--- a/src/unitxt/metrics.py
+++ b/src/unitxt/metrics.py
@@ -480,9 +480,10 @@ def process(
             ) -> Generator:
                 yield from wo_stream
 
-        self.instance_filters.append(WideOpen(condition="eq", values={}))
-
-        for instance_filter in self.instance_filters:
+        for instance_filter in [
+            *self.instance_filters,
+            WideOpen(condition="eq", values={}),
+        ]:
             if isoftype(instance_filter, WideOpen):
                 subset_prefix = ""
             else: