diff --git a/src/json.c b/src/json.c
index e2a0113..66b8bf9 100644
--- a/src/json.c
+++ b/src/json.c
@@ -310,6 +310,7 @@
 	case VAR_INSTR:
 	case VAR_CLASS:
 	case VAR_OBJECT:
+	case VAR_TYPEALIAS:
 	    semsg(_(e_cannot_json_encode_str), vartype_name(val->v_type));
 	    return FAIL;