diff --git a/arekit/common/data/input/providers/rows/samples.py b/arekit/common/data/input/providers/rows/samples.py
index cf90ea2e..7c0f745f 100644
--- a/arekit/common/data/input/providers/rows/samples.py
+++ b/arekit/common/data/input/providers/rows/samples.py
@@ -87,7 +87,7 @@ def __assign_value(column, value):
 
         # Entity indicies from the related context.
         entities = list(filter(lambda term: isinstance(term, Entity), sentence_terms))
-        entity_inds = [i for i, t in sentence_terms if isinstance(t, Entity)]
+        entity_inds = [str(i) for i, t in enumerate(sentence_terms) if isinstance(t, Entity)]
         row[const.ENTITY_VALUES] = ",".join([e.Value.replace(',', '') for e in entities])
         row[const.ENTITY_TYPES] = ",".join([e.Type.replace(',', '') for e in entities])
         row[const.ENTITIES] = ",".join(entity_inds)