diff --git a/src/build_reference_db.c b/src/build_reference_db.c
index 10c735c..d65df7d 100755
--- a/src/build_reference_db.c
+++ b/src/build_reference_db.c
@@ -224,20 +224,30 @@ int build_reference_db(const char* dms_name,
 		// Read line index
 		idx1 = obi_get_int_with_elt_idx_and_col_p_in_view(matrix_with_lca_view, matrix_idx1_column, i, 0);
 		taxid1 = obi_get_int_with_elt_idx_and_col_p_in_view(refs_view, refs_taxid_column, idx1, 0);
+		if (taxid1 == OBIInt_NA)
+		{
+			obidebug(1, "\nError getting a taxid when building a reference database, seq %lld in refs view has no taxid associated", idx1);
+			return -1;
+		}
 		taxon1 = obi_taxo_get_taxon_with_taxid(tax, taxid1);
 		if (taxon1 == NULL)
 		{
-			obidebug(1, "\nError getting a taxon with taxid %d when building a reference database", taxid1);
+			obidebug(1, "\nError getting a taxon with taxid %d when building a reference database, seq %lld in refs view", taxid1, idx1);
 			return -1;
 		}
 
 		// Read taxid2 and get taxon2
 		idx2 = obi_get_int_with_elt_idx_and_col_p_in_view(matrix_with_lca_view, matrix_idx2_column, i, 0);
 		taxid2 = obi_get_int_with_elt_idx_and_col_p_in_view(refs_view, refs_taxid_column, idx2, 0);
+		if (taxid2 == OBIInt_NA)
+		{
+			obidebug(1, "\nError getting a taxid when building a reference database, seq %lld in refs view has no taxid associated", idx1);
+			return -1;
+		}
 		taxon2 = obi_taxo_get_taxon_with_taxid(tax, taxid2);
 		if (taxon2 == NULL)
 		{
-			obidebug(1, "\nError getting a taxon with taxid %d when building a reference database", taxid2);
+			obidebug(1, "\nError getting a taxon with taxid %d when building a reference database, seq %lld in refs view", taxid2, idx2);
 			return -1;
 		}
 
@@ -657,6 +667,20 @@ int build_reference_db(const char* dms_name,
 		obidebug(1, "\nError closing the final view after building a reference database");
 		return -1;
 	}
+
+	// Delete temporary views
+	if (obi_delete_view(dms, matrix_view_name) < 0)
+	{
+		obidebug(1, "\nError deleting temporary view %s after building a reference database", matrix_view_name);
+		return -1;
+	}
+	if (obi_delete_view(dms, matrix_with_lca_view_name) < 0)
+	{
+		obidebug(1, "\nError deleting temporary view %s after building a reference database", matrix_view_name);
+		return -1;
+	}
+
+	// Close DMS
 	if (obi_close_dms(dms, false) < 0)
 	{
 		obidebug(1, "\nError closing the DMS after building a reference database");