diff --git a/FirebaseRemoteConfig/Tests/Swift/FakeUtils/MockURLProtocol.swift b/FirebaseRemoteConfig/Tests/Swift/FakeUtils/MockURLProtocol.swift
new file mode 100644
index 00000000000..7761e4e523d
--- /dev/null
+++ b/FirebaseRemoteConfig/Tests/Swift/FakeUtils/MockURLProtocol.swift
@@ -0,0 +1,62 @@
+// Copyright 2020 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import Foundation
+
+class MockURLProtocol: URLProtocol {
+  #if compiler(>=6)
+    nonisolated(unsafe) static var requestHandler: ((URLRequest) throws -> (
+      Data,
+      HTTPURLResponse
+    ))?
+  #else
+    static var requestHandler: ((URLRequest) throws -> (
+      Data,
+      HTTPURLResponse
+    ))?
+  #endif
+
+  override class func canInit(with request: URLRequest) -> Bool {
+    #if os(watchOS)
+      print("MockURLProtocol cannot be used on watchOS.")
+      return false
+    #else
+      return true
+    #endif // os(watchOS)
+  }
+
+  override class func canonicalRequest(for request: URLRequest) -> URLRequest {
+    return request
+  }
+
+  override func startLoading() {
+    guard let requestHandler = MockURLProtocol.requestHandler else {
+      fatalError("`requestHandler` is nil.")
+    }
+    guard let client = client else {
+      fatalError("`client` is nil.")
+    }
+
+    do {
+      let (data, respopnse) = try requestHandler(request)
+      client.urlProtocol(self, didReceive: respopnse, cacheStoragePolicy: .notAllowed)
+      client.urlProtocol(self, didLoad: data)
+      client.urlProtocolDidFinishLoading(self)
+    } catch {
+      client.urlProtocol(self, didFailWithError: error)
+    }
+  }
+
+  override func stopLoading() {}
+}
diff --git a/FirebaseRemoteConfig/Tests/Swift/FakeUtils/URLSessionPartialMock.swift b/FirebaseRemoteConfig/Tests/Swift/FakeUtils/URLSessionPartialMock.swift
deleted file mode 100644
index f6809a0560e..00000000000
--- a/FirebaseRemoteConfig/Tests/Swift/FakeUtils/URLSessionPartialMock.swift
+++ /dev/null
@@ -1,65 +0,0 @@
-// Copyright 2020 Google LLC
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-import Foundation
-
-#if SWIFT_PACKAGE
-  import RemoteConfigFakeConsoleObjC
-#endif
-
-// Create a partial mock by subclassing the URLSessionDataTask.
-class URLSessionDataTaskMock: URLSessionDataTask, @unchecked Sendable {
-  private let closure: () -> Void
-
-  init(closure: @escaping () -> Void) {
-    self.closure = closure
-  }
-
-  override func resume() {
-    closure()
-  }
-}
-
-class URLSessionMock: URLSession, @unchecked Sendable {
-  typealias CompletionHandler = (Data?, URLResponse?, Error?) -> Void
-
-  private let fakeConsole: FakeConsole
-  init(with fakeConsole: FakeConsole) {
-    self.fakeConsole = fakeConsole
-  }
-
-  // Properties to control what gets returned to the URLSession callback.
-  // error could also be added here.
-  var data: Data?
-  var response: URLResponse?
-  var etag = ""
-
-  override func dataTask(with request: URLRequest,
-                         completionHandler: @escaping (Data?, URLResponse?, Error?) -> Void)
-    -> URLSessionDataTask {
-    let consoleValues = fakeConsole.get()
-    if etag == "" || consoleValues["state"] as! String == RCNFetchResponseKeyStateUpdate {
-      // Time string in microseconds to insure a different string from previous change.
-      etag = String(NSDate().timeIntervalSince1970)
-    }
-    let jsonData = try! JSONSerialization.data(withJSONObject: consoleValues)
-    let response = HTTPURLResponse(url: URL(fileURLWithPath: "fakeURL"),
-                                   statusCode: 200,
-                                   httpVersion: nil,
-                                   headerFields: ["etag": etag])
-    return URLSessionDataTaskMock {
-      completionHandler(jsonData, response, nil)
-    }
-  }
-}
diff --git a/FirebaseRemoteConfig/Tests/Swift/SwiftAPI/APITestBase.swift b/FirebaseRemoteConfig/Tests/Swift/SwiftAPI/APITestBase.swift
index 8aa741f0437..d48600d0f24 100644
--- a/FirebaseRemoteConfig/Tests/Swift/SwiftAPI/APITestBase.swift
+++ b/FirebaseRemoteConfig/Tests/Swift/SwiftAPI/APITestBase.swift
@@ -88,7 +88,24 @@ class APITestBase: XCTestCase {
         config.configRealtime = RealtimeMocks.mockRealtime(config.configRealtime)
       }
       fakeConsole = FakeConsole()
-      config.configFetch.fetchSession = URLSessionMock(with: fakeConsole)
+      let configuration = URLSessionConfiguration.default
+      configuration.protocolClasses = [MockURLProtocol.self]
+      config.configFetch.fetchSession = URLSession(configuration: configuration)
+
+      var etag = ""
+      MockURLProtocol.requestHandler = { request in
+        let consoleValues = self.fakeConsole.get()
+        if etag == "" || consoleValues["state"] as! String == RCNFetchResponseKeyStateUpdate {
+          // Time string in microseconds to insure a different string from previous change.
+          etag = String(NSDate().timeIntervalSince1970)
+        }
+        let jsonData = try! JSONSerialization.data(withJSONObject: consoleValues)
+        let response = HTTPURLResponse(url: URL(fileURLWithPath: "fakeURL"),
+                                       statusCode: 200,
+                                       httpVersion: nil,
+                                       headerFields: ["etag": etag])
+        return (jsonData, response!)
+      }
 
       fakeConsole.config = [Constants.key1: Constants.value1,
                             Constants.jsonKey: jsonValue,
diff --git a/FirebaseRemoteConfig/Tests/Unit/RCNRemoteConfigTest.m b/FirebaseRemoteConfig/Tests/Unit/RCNRemoteConfigTest.m
index 1021d7014d1..9786af20cbf 100644
--- a/FirebaseRemoteConfig/Tests/Unit/RCNRemoteConfigTest.m
+++ b/FirebaseRemoteConfig/Tests/Unit/RCNRemoteConfigTest.m
@@ -1916,7 +1916,7 @@ - (void)testSetCustomSignalsMultipleTimes {
     [_configInstances[i] setCustomSignals:testSignals1
                            withCompletion:^(NSError *_Nullable error) {
                              XCTAssertNil(error);
-                             [_configInstances[i]
+                             [self->_configInstances[i]
                                  setCustomSignals:testSignals2
                                    withCompletion:^(NSError *_Nullable error) {
                                      XCTAssertNil(error);
diff --git a/scripts/build.sh b/scripts/build.sh
index 2925f77d2da..9ad85b209a1 100755
--- a/scripts/build.sh
+++ b/scripts/build.sh
@@ -486,13 +486,12 @@ case "$product-$platform-$method" in
       ../../../FirebaseRemoteConfig/Tests/Swift/AccessToken.json
 
     # Integration tests are only run on iOS to minimize flake failures.
-    # TODO(ncooke3): Remove -sdk and -destination flags.
+    # TODO(ncooke3): Remove -sdk and -destination flags and replace with "${xcb_flags[@]}"
     RunXcodebuild \
       -workspace 'gen/FirebaseRemoteConfig/FirebaseRemoteConfig.xcworkspace' \
       -scheme "FirebaseRemoteConfig-Unit-swift-api-tests" \
       -sdk 'iphonesimulator' \
       -destination 'platform=iOS Simulator,name=iPhone 16,OS=18.3.1' \
-      "${xcb_flags[@]}" \
       build \
       test
     ;;