diff --git a/piker/clearing/_messages.py b/piker/clearing/_messages.py
index b41a565f..fe4d426f 100644
--- a/piker/clearing/_messages.py
+++ b/piker/clearing/_messages.py
@@ -27,6 +27,8 @@ from typing import (
     Literal,
 )
 
+from msgspec import field
+
 from ..data._source import Symbol
 from ..data.types import Struct
 
@@ -250,9 +252,9 @@ class BrokerdStatus(Struct):
     # external: bool = False
 
     # XXX: not required schema as of yet
-    broker_details: dict = {
+    broker_details: dict = field(default_factory=lambda: {
         'name': '',
-    }
+    })
 
 
 class BrokerdFill(Struct):
diff --git a/piker/ui/_display.py b/piker/ui/_display.py
index a9bb5406..475cec55 100644
--- a/piker/ui/_display.py
+++ b/piker/ui/_display.py
@@ -31,6 +31,8 @@ import tractor
 import trio
 import pyqtgraph as pg
 
+from msgspec import field
+
 # from .. import brokers
 from ..data.feed import (
     open_feed,
@@ -151,14 +153,14 @@ class DisplayState(Struct):
     hist_last_price_sticky: YAxisLabel
 
     # misc state tracking
-    vars: dict[str, Any] = {
+    vars: dict[str, Any] = field(default_factory=lambda: {
         'tick_margin': 0,
         'i_last': 0,
         'i_last_append': 0,
         'last_mx_vlm': 0,
         'last_mx': 0,
         'last_mn': 0,
-    }
+    })
 
     vlm_chart: Optional[ChartPlotWidget] = None
     vlm_sticky: Optional[YAxisLabel] = None
diff --git a/piker/ui/_pathops.py b/piker/ui/_pathops.py
index 807cde65..8b3eecaf 100644
--- a/piker/ui/_pathops.py
+++ b/piker/ui/_pathops.py
@@ -27,6 +27,7 @@ import msgspec
 import numpy as np
 from numpy.lib import recfunctions as rfn
 from numba import njit, float64, int64  # , optional
+from msgspec import field
 # import pyqtgraph as pg
 # from PyQt5 import QtGui
 # from PyQt5.QtCore import QLineF, QPointF
@@ -488,7 +489,7 @@ class IncrementalFormatter(msgspec.Struct):
 
 class OHLCBarsFmtr(IncrementalFormatter):
 
-    fields: list[str] = ['open', 'high', 'low', 'close']
+    fields: list[str] = field(default_factory=lambda: ['open', 'high', 'low', 'close'])
 
     def allocate_xy_nd(
         self,