diff --git a/misc-scripts/xref_mapping/xref_config.ini b/misc-scripts/xref_mapping/xref_config.ini
index ce29556548d9a323877bff28f3c56e2cbc758e83..3aa2f66d0c6fa78a00b062b04653c13b972645b7 100644
--- a/misc-scripts/xref_mapping/xref_config.ini
+++ b/misc-scripts/xref_mapping/xref_config.ini
@@ -993,7 +993,6 @@ prio_descr      = main
 parser          = GOSlimParser
 dependent_on    = GO
 release_uri     =
-#data_uri        = script:
 data_uri        = script:host=>ens-staging1,dbname=>ensembl_ontology_74,
 
 [source goslim_goa::EG]
@@ -3079,6 +3078,17 @@ prio_descr      =
 parser          = UniProtAltParser
 release_uri     =
 
+[source Uniprot::ChEMBL]
+# Special source used in UniProtAltParser.  No species uses this source.
+name            = ChEMBL
+download        = N
+order           = 20
+priority        = 1
+prio_descr      =
+parser          = UniProtAltParser
+release_uri     =
+
+
 [source UniParc::MULTI]
 name        = UniParc
 download	  = Y