diff --git a/README.md b/README.md
index 2e7cb1a..3604e5c 100644
--- a/README.md
+++ b/README.md
@@ -147,10 +147,6 @@ import XCTest
 @testable import CacheStoreDemo
 
 class CacheStoreDemoTests: XCTestCase {
-    override func setUp() {
-        TestStoreFailure.handler = XCTFail
-    }
-    
     func testExample_success() throws {
         let store = TestStore(
             initialValues: [
diff --git a/Sources/CacheStore/Stores/Store.swift b/Sources/CacheStore/Stores/Store.swift
index 7e0f57c..3454cb6 100644
--- a/Sources/CacheStore/Stores/Store.swift
+++ b/Sources/CacheStore/Stores/Store.swift
@@ -222,7 +222,7 @@ public class Store<Key: Hashable, Action, Dependency>: ObservableObject, ActionH
 
 // MARK: - Void Dependency
 
-public extension Store {
+public extension Store where Dependency == Void {
     /// Creates a `ScopedStore`
     func scope<ScopedKey: Hashable, ScopedAction>(
         keyTransformation: c.BiDirectionalTransformation<Key?, ScopedKey?>,
diff --git a/Sources/CacheStore/Stores/TestStore.swift b/Sources/CacheStore/Stores/TestStore.swift
index 625f626..fab9dd0 100644
--- a/Sources/CacheStore/Stores/TestStore.swift
+++ b/Sources/CacheStore/Stores/TestStore.swift
@@ -1,13 +1,14 @@
 #if DEBUG
 import CustomDump
 import Foundation
+import XCTestDynamicOverlay
 
 /// Facade typealias for XCTFail without importing XCTest
 public typealias FailureHandler = (_ message: String, _ file: StaticString, _ line: UInt) -> Void
 
 /// Static object to provide the `FailureHandler` to any `TestStore`
 public enum TestStoreFailure {
-    public static var handler: FailureHandler!
+    public static var handler: FailureHandler = XCTestDynamicOverlay.XCTFail
 }
 
 /// Testable `Store` where you can send and receive actions while expecting the changes
@@ -42,18 +43,6 @@ public class TestStore<Key: Hashable, Action, Dependency> {
         file: StaticString = #filePath,
         line: UInt = #line
     ) {
-        assert(
-            TestStoreFailure.handler != nil,
-            """
-            Set `TestStoreFailure.handler`
-                
-                override func setUp() {
-                    TestStoreFailure.handler = XCTFail
-                }
-            
-            """
-        )
-        
         store = Store(initialValues: initialValues, actionHandler: actionHandler, dependency: dependency).debug
         effects = []
         initFile = file