diff --git a/crates/red_knot_python_semantic/resources/mdtest/call/dunder.md b/crates/red_knot_python_semantic/resources/mdtest/call/dunder.md
index 7f8cb0d564..1f31f8bbdd 100644
--- a/crates/red_knot_python_semantic/resources/mdtest/call/dunder.md
+++ b/crates/red_knot_python_semantic/resources/mdtest/call/dunder.md
@@ -204,6 +204,28 @@ def _(flag: bool):
     reveal_type(d[0])  # revealed: str | bytes
 ```
 
+## Calling a union of types without dunder methods
+
+We add instance attributes here to make sure that we don't treat the implicit dunder calls here like
+regular method calls.
+
+```py
+def external_getitem(instance, key: int) -> str:
+    return str(key)
+
+class NotSubscriptable1:
+    def __init__(self, value: int):
+        self.__getitem__ = external_getitem
+
+class NotSubscriptable2:
+    def __init__(self, value: int):
+        self.__getitem__ = external_getitem
+
+def _(union: NotSubscriptable1 | NotSubscriptable2):
+    # error: [non-subscriptable]
+    union[0]
+```
+
 ## Calling a possibly-unbound dunder method
 
 ```py
diff --git a/crates/red_knot_python_semantic/src/types.rs b/crates/red_knot_python_semantic/src/types.rs
index 98da9d3aba..eac89fe2e2 100644
--- a/crates/red_knot_python_semantic/src/types.rs
+++ b/crates/red_knot_python_semantic/src/types.rs
@@ -1963,11 +1963,17 @@ impl<'db> Type<'db> {
 
         match self {
             Type::Union(union) => union
-                .map_with_boundness(db, |elem| elem.member(db, &name).symbol)
+                .map_with_boundness(db, |elem| {
+                    elem.member_lookup_with_policy(db, name_str.into(), policy)
+                        .symbol
+                })
                 .into(),
 
             Type::Intersection(intersection) => intersection
-                .map_with_boundness(db, |elem| elem.member(db, &name).symbol)
+                .map_with_boundness(db, |elem| {
+                    elem.member_lookup_with_policy(db, name_str.into(), policy)
+                        .symbol
+                })
                 .into(),
 
             Type::Dynamic(..) | Type::Never => Symbol::bound(self).into(),