diff --git a/src/obidms.c b/src/obidms.c
index 5d0e177..6f83334 100644
--- a/src/obidms.c
+++ b/src/obidms.c
@@ -561,7 +561,7 @@ Obi_indexer_p obi_dms_get_indexer_from_list(OBIDMS_p dms, const char* indexer_na
 }
 
 
-void obi_dms_list_indexer(OBIDMS_p dms, Obi_indexer_p indexer)
+void obi_dms_list_indexer(OBIDMS_p dms, Obi_indexer_p indexer)  	// TODO add check if indexer already in list?
 {
 	*(((dms->opened_indexers)->indexers)+((dms->opened_indexers)->nb_opened_indexers)) = indexer;
 	((dms->opened_indexers)->nb_opened_indexers)++;
diff --git a/src/obidms.h b/src/obidms.h
index 04348c0..3f332bc 100644
--- a/src/obidms.h
+++ b/src/obidms.h
@@ -230,6 +230,8 @@ OBIDMS_column_p obi_dms_get_column_from_list(OBIDMS_p dms, const char* column_na
 /**
  * @brief Adds a column identified by its name and its version number in the list of opened columns.
  *
+ * @warning obi_dms_get_column_from_list() should be used first to check if the column isn't already listed.
+ *
  * @param dms The OBIDMS.
  * @param column A pointer on the column that should be added in the list of opened columns.
  *
@@ -269,6 +271,8 @@ Obi_indexer_p obi_dms_get_indexer_from_list(OBIDMS_p dms, const char* indexer_na
 /**
  * @brief Adds an indexer identified by its name in the list of opened indexers.
  *
+ * @warning obi_dms_get_indexer_from_list() should be used first to check if the indexer isn't already listed.
+ *
  * @param dms The OBIDMS.
  * @param indexer A pointer on the indexer that should be added in the list of opened indexers.
  *