diff --git a/cirq-core/cirq/work/observable_measurement.py b/cirq-core/cirq/work/observable_measurement.py
index f31f3ab59be..5a8ccc7a900 100644
--- a/cirq-core/cirq/work/observable_measurement.py
+++ b/cirq-core/cirq/work/observable_measurement.py
@@ -531,7 +531,7 @@ def measure_grouped_settings(
     for max_setting, param_resolver in itertools.product(
         grouped_settings.keys(), study.to_resolvers(circuit_sweep)
     ):
-        circuit_params = dict(param_resolver.param_dict)
+        circuit_params = param_resolver.param_dict
         meas_spec = _MeasurementSpec(max_setting=max_setting, circuit_params=circuit_params)
         accumulator = BitstringAccumulator(
             meas_spec=meas_spec,
diff --git a/cirq-core/cirq/work/observable_measurement_data.py b/cirq-core/cirq/work/observable_measurement_data.py
index 95459ddef7b..9936eed2f0d 100644
--- a/cirq-core/cirq/work/observable_measurement_data.py
+++ b/cirq-core/cirq/work/observable_measurement_data.py
@@ -14,7 +14,7 @@
 
 import dataclasses
 import datetime
-from typing import Any, Dict, Iterable, List, Tuple, TYPE_CHECKING, Union
+from typing import Any, Dict, Iterable, List, Mapping, Tuple, TYPE_CHECKING, Union
 
 import numpy as np
 import sympy
@@ -107,7 +107,7 @@ class ObservableMeasuredResult:
     mean: float
     variance: float
     repetitions: int
-    circuit_params: Dict[Union[str, sympy.Expr], Union[value.Scalar, sympy.Expr]]
+    circuit_params: Mapping[Union[str, sympy.Expr], Union[value.Scalar, sympy.Expr]]
 
     def __repr__(self):
         # I wish we could use the default dataclass __repr__ but
diff --git a/cirq-core/cirq/work/observable_settings.py b/cirq-core/cirq/work/observable_settings.py
index 1a265cb5b6f..677297fbc91 100644
--- a/cirq-core/cirq/work/observable_settings.py
+++ b/cirq-core/cirq/work/observable_settings.py
@@ -14,7 +14,17 @@
 
 import dataclasses
 import numbers
-from typing import Union, Iterable, Dict, Optional, TYPE_CHECKING, ItemsView, Tuple, FrozenSet
+from typing import (
+    AbstractSet,
+    Mapping,
+    Union,
+    Iterable,
+    Dict,
+    Optional,
+    TYPE_CHECKING,
+    Tuple,
+    FrozenSet,
+)
 
 import sympy
 
@@ -143,7 +153,8 @@ def _fix_precision(val: Union[value.Scalar, sympy.Expr], precision) -> Union[int
 
 
 def _hashable_param(
-    param_tuples: ItemsView[Union[str, sympy.Expr], Union[value.Scalar, sympy.Expr]], precision=1e7
+    param_tuples: AbstractSet[Tuple[Union[str, sympy.Expr], Union[value.Scalar, sympy.Expr]]],
+    precision=1e7,
 ) -> FrozenSet[Tuple[str, Union[int, Tuple[int, int]]]]:
     """Hash circuit parameters using fixed precision.
 
@@ -166,7 +177,7 @@ class _MeasurementSpec:
     """
 
     max_setting: InitObsSetting
-    circuit_params: Dict[Union[str, sympy.Expr], Union[value.Scalar, sympy.Expr]]
+    circuit_params: Mapping[Union[str, sympy.Expr], Union[value.Scalar, sympy.Expr]]
 
     def __hash__(self):
         return hash((self.max_setting, _hashable_param(self.circuit_params.items())))
diff --git a/cirq-core/cirq/work/sampler.py b/cirq-core/cirq/work/sampler.py
index 2184cad4687..2ccf9477659 100644
--- a/cirq-core/cirq/work/sampler.py
+++ b/cirq-core/cirq/work/sampler.py
@@ -352,8 +352,8 @@ def sample_expectation_values(
 
         # Flatten Circuit Sweep into one big list of Params.
         # Keep track of their indices so we can map back.
-        flat_params: List['cirq.ParamDictType'] = [
-            dict(pr.param_dict) for pr in study.to_resolvers(params)
+        flat_params: List['cirq.ParamMappingType'] = [
+            pr.param_dict for pr in study.to_resolvers(params)
         ]
         circuit_param_to_sweep_i: Dict[FrozenSet[Tuple[str, Union[int, Tuple[int, int]]]], int] = {
             _hashable_param(param.items()): i for i, param in enumerate(flat_params)