diff --git a/corrscope/channel.py b/corrscope/channel.py
index 3a0d456..45ef4e2 100644
--- a/corrscope/channel.py
+++ b/corrscope/channel.py
@@ -4,7 +4,7 @@ from typing import TYPE_CHECKING, Optional, Union, Dict, Any
 import attr
 from ruamel.yaml.comments import CommentedMap
 
-from corrscope.config import DumpableAttrs, Alias, CorrError
+from corrscope.config import DumpableAttrs, Alias, CorrError, evolve_compat
 from corrscope.triggers import MainTriggerConfig
 from corrscope.util import coalesce
 from corrscope.wave import Wave, Flatten
@@ -88,12 +88,15 @@ class Channel:
         # Create a Trigger object.
         if isinstance(cfg.trigger, MainTriggerConfig):
             tcfg = cfg.trigger
+
         elif isinstance(
             cfg.trigger, (CommentedMap, dict)
         ):  # CommentedMap may/not be subclass of dict.
-            tcfg = attr.evolve(corr_cfg.trigger, **cfg.trigger)
+            tcfg = evolve_compat(corr_cfg.trigger, **cfg.trigger)
+
         elif cfg.trigger is None:
             tcfg = corr_cfg.trigger
+
         else:
             raise CorrError(
                 f"invalid per-channel trigger {cfg.trigger}, type={type(cfg.trigger)}, "
diff --git a/corrscope/config.py b/corrscope/config.py
index bc3b7c3..f4df35e 100644
--- a/corrscope/config.py
+++ b/corrscope/config.py
@@ -23,6 +23,7 @@ __all__ = [
     "yaml",
     "copy_config",
     "DumpableAttrs",
+    "evolve_compat",
     "KeywordAttrs",
     "with_units",
     "get_units",
@@ -190,10 +191,14 @@ class DumpableAttrs:
 
     # SafeConstructor.construct_yaml_object() uses __setstate__ to load objects.
     def __setstate__(self, state: Dict[str, Any]) -> None:
+        self.__dict__ = self.new_from_state(state).__dict__
+
+    # If called via instance, cls == type(self).
+    @classmethod
+    def new_from_state(cls: Type[T], state: Dict[str, Any]) -> T:
         """ Redirect `Alias(key)=value` to `key=value`.
         Then call the dataclass constructor (to validate parameters). """
 
-        cls = type(self)
         cls_name = cls.__name__
         fields = attr.fields_dict(cls)
 
@@ -225,8 +230,14 @@ class DumpableAttrs:
                 new_state[key] = value
 
         del state
-        obj = cls(**new_state)
-        self.__dict__ = obj.__dict__
+        return cls(**new_state)
+
+
+def evolve_compat(obj: DumpableAttrs, **changes):
+    """Evolve an object, based on user-specified dict,
+    while ignoring unrecognized keywords."""
+    # In dictionaries, later values will always override earlier ones
+    return obj.new_from_state({**obj.__dict__, **changes})
 
 
 class KeywordAttrs(DumpableAttrs):