diff --git a/openfeature/client.py b/openfeature/client.py
index d73a3800..29e3a32a 100644
--- a/openfeature/client.py
+++ b/openfeature/client.py
@@ -1,5 +1,6 @@
 import logging
 import typing
+from collections.abc import Awaitable
 from dataclasses import dataclass
 
 from openfeature import _event_support, api
@@ -37,46 +38,6 @@
 
 logger = logging.getLogger("openfeature")
 
-GetDetailCallable = typing.Union[
-    typing.Callable[
-        [str, bool, typing.Optional[EvaluationContext]], FlagResolutionDetails[bool]
-    ],
-    typing.Callable[
-        [str, int, typing.Optional[EvaluationContext]], FlagResolutionDetails[int]
-    ],
-    typing.Callable[
-        [str, float, typing.Optional[EvaluationContext]], FlagResolutionDetails[float]
-    ],
-    typing.Callable[
-        [str, str, typing.Optional[EvaluationContext]], FlagResolutionDetails[str]
-    ],
-    typing.Callable[
-        [str, typing.Union[dict, list], typing.Optional[EvaluationContext]],
-        FlagResolutionDetails[typing.Union[dict, list]],
-    ],
-]
-GetDetailCallableAsync = typing.Union[
-    typing.Callable[
-        [str, bool, typing.Optional[EvaluationContext]],
-        typing.Awaitable[FlagResolutionDetails[bool]],
-    ],
-    typing.Callable[
-        [str, int, typing.Optional[EvaluationContext]],
-        typing.Awaitable[FlagResolutionDetails[int]],
-    ],
-    typing.Callable[
-        [str, float, typing.Optional[EvaluationContext]],
-        typing.Awaitable[FlagResolutionDetails[float]],
-    ],
-    typing.Callable[
-        [str, str, typing.Optional[EvaluationContext]],
-        typing.Awaitable[FlagResolutionDetails[str]],
-    ],
-    typing.Callable[
-        [str, typing.Union[dict, list], typing.Optional[EvaluationContext]],
-        typing.Awaitable[FlagResolutionDetails[typing.Union[dict, list]]],
-    ],
-]
 TypeMap = dict[
     FlagType,
     typing.Union[
@@ -88,6 +49,26 @@
     ],
 ]
 
+T = typing.TypeVar("T", bool, int, float, str, typing.Union[dict, list])
+
+
+class ResolveDetailsCallable(typing.Protocol[T]):
+    def __call__(
+        self,
+        flag_key: str,
+        default_value: T,
+        evaluation_context: typing.Optional[EvaluationContext],
+    ) -> FlagResolutionDetails[T]: ...
+
+
+class ResolveDetailsCallableAsync(typing.Protocol[T]):
+    def __call__(
+        self,
+        flag_key: str,
+        default_value: T,
+        evaluation_context: typing.Optional[EvaluationContext],
+    ) -> Awaitable[FlagResolutionDetails[T]]: ...
+
 
 @dataclass
 class ClientMetadata:
@@ -702,7 +683,7 @@ async def _create_provider_evaluation_async(
         evaluation_context: typing.Optional[EvaluationContext] = None,
     ) -> FlagEvaluationDetails[typing.Any]:
         get_details_callables_async: typing.Mapping[
-            FlagType, GetDetailCallableAsync
+            FlagType, ResolveDetailsCallableAsync
         ] = {
             FlagType.BOOLEAN: provider.resolve_boolean_details_async,
             FlagType.INTEGER: provider.resolve_integer_details_async,
@@ -714,7 +695,7 @@ async def _create_provider_evaluation_async(
         if not get_details_callable:
             raise GeneralError(error_message="Unknown flag type")
 
-        resolution = await get_details_callable(  # type: ignore[call-arg]
+        resolution = await get_details_callable(
             flag_key=flag_key,
             default_value=default_value,
             evaluation_context=evaluation_context,
@@ -752,7 +733,7 @@ def _create_provider_evaluation(
         :return: a FlagEvaluationDetails object with the fully evaluated flag from a
         provider
         """
-        get_details_callables: typing.Mapping[FlagType, GetDetailCallable] = {
+        get_details_callables: typing.Mapping[FlagType, ResolveDetailsCallable] = {
             FlagType.BOOLEAN: provider.resolve_boolean_details,
             FlagType.INTEGER: provider.resolve_integer_details,
             FlagType.FLOAT: provider.resolve_float_details,
@@ -764,7 +745,7 @@ def _create_provider_evaluation(
         if not get_details_callable:
             raise GeneralError(error_message="Unknown flag type")
 
-        resolution = get_details_callable(  # type: ignore[call-arg]
+        resolution = get_details_callable(
             flag_key=flag_key,
             default_value=default_value,
             evaluation_context=evaluation_context,