diff --git a/ext/rbs_extension/ast_translation.c b/ext/rbs_extension/ast_translation.c
index 3b88cbd2d..b19937aa1 100644
--- a/ext/rbs_extension/ast_translation.c
+++ b/ext/rbs_extension/ast_translation.c
@@ -87,6 +87,8 @@ VALUE rbs_attr_ivar_name_to_ruby(rbs_translation_context_t ctx, rbs_attr_ivar_na
         return Qnil;
     case RBS_ATTR_IVAR_NAME_TAG_EMPTY:
         return Qfalse;
+    default:
+        rb_fatal("unknown enum rbs_attr_ivar_name_tag ivar_name.tag: %d", ivar_name.tag);
     }
 }
 
diff --git a/src/parser.c b/src/parser.c
index 2a83dc9c2..be238c759 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -519,7 +519,7 @@ static bool parse_params(rbs_parser_t *parser, method_params *params, bool self_
 PARSE_OPTIONAL_PARAMS:
     while (true) {
         switch (parser->next_token.type) {
-        case pQUESTION:
+        case pQUESTION: {
             rbs_parser_advance(parser);
 
             if (is_keyword(parser)) {
@@ -533,6 +533,7 @@ static bool parse_params(rbs_parser_t *parser, method_params *params, bool self_
             rbs_node_list_append(params->optional_positionals, (rbs_node_t *) param);
 
             break;
+        }
         default:
             goto PARSE_REST_PARAM;
         }
@@ -597,13 +598,13 @@ static bool parse_params(rbs_parser_t *parser, method_params *params, bool self_
             }
             break;
 
-        case pSTAR2:
+        case pSTAR2: {
             rbs_parser_advance(parser);
             rbs_types_function_param_t *param = NULL;
             CHECK_PARSE(parse_function_param(parser, &param, self_allowed, classish_allowed));
             params->rest_keywords = (rbs_node_t *) param;
             break;
-
+        }
         case tUIDENT:
         case tLIDENT:
         case tQIDENT:
diff --git a/templates/ext/rbs_extension/ast_translation.c.erb b/templates/ext/rbs_extension/ast_translation.c.erb
index 59e2af0a8..cf4dba4be 100644
--- a/templates/ext/rbs_extension/ast_translation.c.erb
+++ b/templates/ext/rbs_extension/ast_translation.c.erb
@@ -78,8 +78,10 @@ VALUE rbs_attr_ivar_name_to_ruby(rbs_translation_context_t ctx, rbs_attr_ivar_na
     }
     case RBS_ATTR_IVAR_NAME_TAG_UNSPECIFIED:
         return Qnil;
-    case RBS_ATTR_IVAR_NAME_TAG_EMPTY: 
+    case RBS_ATTR_IVAR_NAME_TAG_EMPTY:
         return Qfalse;
+    default:
+        rb_fatal("unknown enum rbs_attr_ivar_name_tag ivar_name.tag: %d", ivar_name.tag);
     }
 }