diff --git a/tools/perf/util/trace-event-parse.c b/tools/perf/util/trace-event-parse.c
index e0a4f652f289..a4088ced1e64 100644
--- a/tools/perf/util/trace-event-parse.c
+++ b/tools/perf/util/trace-event-parse.c
@@ -1423,6 +1423,11 @@ static long long arg_num_eval(struct print_arg *arg)
 				die("unknown op '%s'", arg->op.op);
 			}
 			break;
+		case '+':
+			left = arg_num_eval(arg->op.left);
+			right = arg_num_eval(arg->op.right);
+			val = left + right;
+			break;
 		default:
 			die("unknown op '%s'", arg->op.op);
 		}
@@ -1483,6 +1488,13 @@ process_fields(struct event *event, struct print_flag_sym **list, char **tok)
 
 		free_token(token);
 		type = process_arg(event, arg, &token);
+
+		if (type == EVENT_OP)
+			type = process_op(event, arg, &token);
+
+		if (type == EVENT_ERROR)
+			goto out_free;
+
 		if (test_type_token(type, token, EVENT_DELIM, ","))
 			goto out_free;