diff --git a/biokb/utils.py b/biokb/utils.py
index 092c7926ce7179636392e8494de577fd69bf5cb7..270a7ec7c695b12f3b9c59864c28549972db5205 100644
--- a/biokb/utils.py
+++ b/biokb/utils.py
@@ -1,5 +1,10 @@
-def uri_to_code(uri: str) -> str:
-    """Translates URIs such as http://lcsb.uni.lu/biokb/entities/BTO_0001043 to BTO_0001043
+def standarise_underscored_entity_code(entity_code: str) -> str:
+    return entity_code.replace(':', '_', 1)
+
+
+def uri_to_entity_code(uri: str) -> str:
+    """Translates URIs such as http://lcsb.uni.lu/biokb/entities/BTO_0001043 to BTO:0001043
+    Replaces only the first underscore with colon.
 
     Arguments:
         uri {str} -- [description]
@@ -7,4 +12,4 @@ def uri_to_code(uri: str) -> str:
     Returns:
         str -- [description]
     """
-    return uri.split('/')[-1]
+    return uri.split('/')[-1].replace('_', ':', 1)