diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index ef2c65f91677..cdb32c78d150 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -1592,7 +1592,7 @@ static int get_op_prio(char *op)
 		case '?':
 			return 16;
 		default:
-			die("unknown op '%c'", op[0]);
+			do_warning("unknown op '%c'", op[0]);
 			return -1;
 		}
 	} else {
@@ -1613,22 +1613,22 @@ static int get_op_prio(char *op)
 		} else if (strcmp(op, "||") == 0) {
 			return 15;
 		} else {
-			die("unknown op '%s'", op);
+			do_warning("unknown op '%s'", op);
 			return -1;
 		}
 	}
 }
 
-static void set_op_prio(struct print_arg *arg)
+static int set_op_prio(struct print_arg *arg)
 {
 
 	/* single ops are the greatest */
-	if (!arg->op.left || arg->op.left->type == PRINT_NULL) {
+	if (!arg->op.left || arg->op.left->type == PRINT_NULL)
 		arg->op.prio = 0;
-		return;
-	}
+	else
+		arg->op.prio = get_op_prio(arg->op.op);
 
-	arg->op.prio = get_op_prio(arg->op.op);
+	return arg->op.prio;
 }
 
 /* Note, *tok does not get freed, but will most likely be saved */
@@ -1710,7 +1710,10 @@ process_op(struct event_format *event, struct print_arg *arg, char **tok)
 		arg->op.op = token;
 		arg->op.left = left;
 
-		set_op_prio(arg);
+		if (set_op_prio(arg) == -1) {
+			event->flags |= EVENT_FL_FAILED;
+			goto out_free;
+		}
 
 		type = read_token_item(&token);
 		*tok = token;