diff --git a/milli/src/search/query_tree.rs b/milli/src/search/query_tree.rs
index 4eccae8ce..7d13f27a3 100644
--- a/milli/src/search/query_tree.rs
+++ b/milli/src/search/query_tree.rs
@@ -623,7 +623,9 @@ mod test {
         }
 
         fn exact_words(&self) -> crate::Result<fst::Set<Cow<[u8]>>> {
-            Ok(fst::Set::new(Cow::Borrowed(self.exact_words.as_slice())).unwrap())
+            let builder = fst::SetBuilder::new(Vec::new()).unwrap();
+            let data = builder.into_inner().unwrap();
+            Ok(fst::Set::new(Cow::Owned(data)).unwrap())
         }
     }