diff --git a/scripts/gen_genesis.ml b/scripts/gen_genesis.ml
index e5fc3ed67..fda432524 100644
--- a/scripts/gen_genesis.ml
+++ b/scripts/gen_genesis.ml
@@ -56,7 +56,7 @@ let _ =
 let sed =
   Format.sprintf
     "sed -E -i \
-     -e 's/name = \"(TEZOS[A_Z]+)[^\"]*\" ;/name = \"\\1%s\" ;/' \
+     -e 's/name = \"(TEZOS[_A-Z]+)[^\"]*\" ;/name = \"\\1%s\" ;/' \
      ../src/lib_shell/distributed_db_message.ml"
     date