diff --git a/dmt/A_mappers/learn_CHOICE_enums.py b/dmt/A_mappers/learn_CHOICE_enums.py
index 5db1b924a72cd3c0b9f121f2112d4ca6418cab9b..44396b232ca2d4ce0ab7e2b14bb1c4557651d111 100644
--- a/dmt/A_mappers/learn_CHOICE_enums.py
+++ b/dmt/A_mappers/learn_CHOICE_enums.py
@@ -31,7 +31,7 @@ enums_dump = "\n    ".join(
 )
 
 enums_dump += "\n    ".join(
-    'printf("%s = %d\\n");' % (name.strip(), val.replace('LL',''))
+    'printf("{} = {}\\n");'.format(name.strip(), val.replace('LL', ''))
     for name, val in enums
 )
 uniq = os.getpid()