diff --git a/src/obidmscolumn_array.c b/src/obidmscolumn_array.c
index 73e0aab..2fb1e57 100755
--- a/src/obidmscolumn_array.c
+++ b/src/obidmscolumn_array.c
@@ -71,13 +71,19 @@ const void* obi_column_get_array(OBIDMS_column_p column, index_t line_nb, int32_
 	index_t idx;
 
 	if (obi_column_prepare_to_get_value(column, line_nb) < 0)
+	{
+		*value_length_p = -1;
 		return OBITuple_NA;
+	}
 
 	idx = *(((index_t*) (column->data)) + line_nb);
 
 	// Check NA
 	if (idx == OBIIdx_NA)
+	{
+		*value_length_p = 0;
 		return OBITuple_NA;
+	}
 
 	return obi_retrieve_array(column->indexer, idx, value_length_p);
 }