diff --git a/src/builtin.h b/src/builtin.h
index 53c00ad9d..f0c0ca032 100644
--- a/src/builtin.h
+++ b/src/builtin.h
@@ -110,7 +110,7 @@ int parse_help_only_cmd_opts(help_only_cmd_opts_t &opts, int *optind, int argc,
                              const wchar_t **argv, parser_t &parser, io_streams_t &streams);
 
 /// An enum of the builtins implemented in Rust.
-enum RustBuiltin : int32_t {
+enum class RustBuiltin : int32_t {
     Abbr,
     Bg,
     Block,