diff --git a/dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/DataFilter.kt b/dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/DataFilter.kt
index e9392da8..b41c4f30 100644
--- a/dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/DataFilter.kt
+++ b/dataforge-data/src/commonMain/kotlin/space/kscience/dataforge/data/DataFilter.kt
@@ -77,6 +77,7 @@ public class FilteredDataTree<T>(
         }
 }
 
+@OptIn(DFInternal::class)
 public fun <T> DataTree<T>.filterData(
     predicate: DataFilter,
-): FilteredDataTree<T> = FilteredDataTree(this, predicate, Name.EMPTY)
\ No newline at end of file
+): DataTree<T> = FilteredDataTree(this, predicate, Name.EMPTY)
\ No newline at end of file