diff --git a/GoogleUtilities/Example/Tests/Swizzler/GULAppDelegateSwizzlerTest.m b/GoogleUtilities/Example/Tests/Swizzler/GULAppDelegateSwizzlerTest.m
index 1452aec7f84..e9fa793be9d 100644
--- a/GoogleUtilities/Example/Tests/Swizzler/GULAppDelegateSwizzlerTest.m
+++ b/GoogleUtilities/Example/Tests/Swizzler/GULAppDelegateSwizzlerTest.m
@@ -181,7 +181,8 @@ - (BOOL)application:(UIApplication *)application
 
 - (BOOL)application:(UIApplication *)application
     continueUserActivity:(NSUserActivity *)userActivity
-      restorationHandler:(void (^)(NSArray *__nullable restorableObjects))restorationHandler {
+      restorationHandler:(void (^)(NSArray<id<UIUserActivityRestoring>> *__nullable
+                                       restorableObjects))restorationHandler {
   _userActivity = userActivity;
   return YES;
 }
@@ -261,7 +262,7 @@ - (void)testHandleBackgroundSessionMethod {
 
   UIApplication *currentApplication = [UIApplication sharedApplication];
   NSString *sessionID = @"123";
-  void (^nilHandler)() = nil;
+  void (^nilHandler)(void) = nil;
   [realAppDelegate application:currentApplication
       handleEventsForBackgroundURLSession:sessionID
                         completionHandler:nilHandler];
@@ -274,8 +275,11 @@ - (void)testHandleBackgroundSessionMethod {
 
 /** Tests registering and unregistering invalid interceptors. */
 - (void)testInvalidInterceptor {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wnonnull"
   XCTAssertThrows([GULAppDelegateSwizzler registerAppDelegateInterceptor:nil],
                   @"Should not register nil interceptor");
+#pragma clang diagnostic pop
   XCTAssertEqual([GULAppDelegateSwizzler interceptors].count, 0);
 
   // Try to register some random object that does not conform to UIApplicationDelegate.
@@ -303,6 +307,8 @@ - (void)testInvalidInterceptor {
   XCTAssertEqual([GULAppDelegateSwizzler interceptors].count, 1);
 
   // Try to unregister an empty string. Should not remove anything.
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wnonnull"
   XCTAssertThrows([GULAppDelegateSwizzler unregisterAppDelegateInterceptorWithID:nil],
                   @"Should not unregister nil interceptorID");
   XCTAssertEqual([GULAppDelegateSwizzler interceptors].count, 1);
diff --git a/GoogleUtilities/Example/Tests/Swizzler/GULSwizzlerInheritedMethodsSwizzlingTest.m b/GoogleUtilities/Example/Tests/Swizzler/GULSwizzlerInheritedMethodsSwizzlingTest.m
index 48cfd206911..9137b62e3ee 100644
--- a/GoogleUtilities/Example/Tests/Swizzler/GULSwizzlerInheritedMethodsSwizzlingTest.m
+++ b/GoogleUtilities/Example/Tests/Swizzler/GULSwizzlerInheritedMethodsSwizzlingTest.m
@@ -110,15 +110,16 @@ - (void)testSwizzlingAndUnswizzlingInheritedInstanceMethodsForSuperclassesWorksA
   NSString *swizzledPollutedTestObjectSubclassSubclassDescription =
       [originalPollutedTestObjectSubclassSubclassDescription stringByAppendingString:@"SWIZZLED!"];
 
-  NSString * (^newImplementationPollutedTestObject)() = ^NSString *(id _self) {
+  NSString * (^newImplementationPollutedTestObject)(NSString *) = ^NSString *(id _self) {
     return swizzledPollutedTestObjectDescription;
   };
 
-  NSString * (^newImplementationPollutedTestObjectSubclass)() = ^NSString *(id _self) {
+  NSString * (^newImplementationPollutedTestObjectSubclass)(NSString *) = ^NSString *(id _self) {
     return swizzledPollutedTestObjectSubclassDescription;
   };
 
-  NSString * (^newImplementationPollutedTestObjectSubclassSubclass)() = ^NSString *(id _self) {
+  NSString * (^newImplementationPollutedTestObjectSubclassSubclass)(NSString *) =
+      ^NSString *(id _self) {
     return swizzledPollutedTestObjectSubclassSubclassDescription;
   };
 
diff --git a/GoogleUtilities/Example/Tests/Swizzler/GULSwizzlerTest.m b/GoogleUtilities/Example/Tests/Swizzler/GULSwizzlerTest.m
index f7650730a79..e4cd2888f61 100644
--- a/GoogleUtilities/Example/Tests/Swizzler/GULSwizzlerTest.m
+++ b/GoogleUtilities/Example/Tests/Swizzler/GULSwizzlerTest.m
@@ -69,7 +69,7 @@ @implementation GULSwizzlerTest
 - (void)testOriginalImpInstanceMethod {
   Method method = class_getInstanceMethod([NSObject class], @selector(description));
   IMP originalImp = method_getImplementation(method);
-  NSString * (^newImplementation)() = ^NSString *() {
+  NSString * (^newImplementation)(void) = ^NSString *() {
     return @"nonsense";
   };
 
@@ -155,7 +155,7 @@ - (void)testOriginalImpCallThrough {
 - (void)testOriginalImpClassMethod {
   Method method = class_getInstanceMethod([NSObject class], @selector(description));
   IMP originalImp = method_getImplementation(method);
-  NSString * (^newImplementation)() = ^NSString *() {
+  NSString * (^newImplementation)(void) = ^NSString *() {
     return @"nonsense";
   };
 
@@ -179,7 +179,7 @@ - (void)testOriginalImpInstanceAndClassImpsAreDifferent {
   IMP instanceImp = method_getImplementation(instanceMethod);
   IMP classImp = method_getImplementation(classMethod);
 
-  NSString * (^newImplementation)() = ^NSString *() {
+  NSString * (^newImplementation)(void) = ^NSString *() {
     return @"nonsense";
   };
 
@@ -208,7 +208,7 @@ - (void)testOriginalImpInstanceAndClassImpsAreDifferent {
 /** Tests swizzling an instance method. */
 - (void)testSwizzleInstanceMethod {
   NSString *swizzledDescription = @"Not what you expected!";
-  NSString * (^newImplementation)() = ^NSString *() {
+  NSString * (^newImplementation)(void) = ^NSString *() {
     return swizzledDescription;
   };
 
@@ -224,7 +224,7 @@ - (void)testSwizzleInstanceMethod {
 /** Tests swizzling a class method. */
 - (void)testSwizzleClassMethod {
   NSString *swizzledDescription = @"Swizzled class description";
-  NSString * (^newImplementation)() = ^NSString *() {
+  NSString * (^newImplementation)(void) = ^NSString *() {
     return swizzledDescription;
   };
 
@@ -241,7 +241,7 @@ - (void)testUnswizzleInstanceMethod {
   NSObject *object = [[NSObject alloc] init];
   NSString *originalDescription = [object description];
   NSString *swizzledDescription = @"Swizzled description";
-  NSString * (^newImplementation)() = ^NSString *() {
+  NSString * (^newImplementation)(void) = ^NSString *() {
     return swizzledDescription;
   };
 
@@ -260,7 +260,7 @@ - (void)testUnswizzleInstanceMethod {
 - (void)testUnswizzleClassMethod {
   NSString *originalDescription = [NSObject description];
   NSString *swizzledDescription = @"Swizzled class description";
-  NSString * (^newImplementation)() = ^NSString *() {
+  NSString * (^newImplementation)(void) = ^NSString *() {
     return swizzledDescription;
   };
 
@@ -276,7 +276,7 @@ - (void)testUnswizzleClassMethod {
 /** Tests swizzling a class method doesn't swizzle an instance method of the same name. */
 - (void)testSwizzlingAClassMethodDoesntSwizzleAnInstanceMethod {
   NSString *swizzledDescription = @"Swizzled class description";
-  NSString * (^newImplementation)() = ^NSString *() {
+  NSString * (^newImplementation)(void) = ^NSString *() {
     return swizzledDescription;
   };
 
@@ -292,7 +292,7 @@ - (void)testSwizzlingAClassMethodDoesntSwizzleAnInstanceMethod {
 /** Tests swizzling an instance method doesn't swizzle a class method of the same name. */
 - (void)testSwizzlingAnInstanceMethodDoesntSwizzleAClassMethod {
   NSString *swizzledDescription = @"Not what you expected!";
-  NSString * (^newImplementation)() = ^NSString *() {
+  NSString * (^newImplementation)(void) = ^NSString *() {
     return swizzledDescription;
   };
 
@@ -310,7 +310,7 @@ - (void)testSwizzlingAnInstanceMethodDoesntSwizzleAClassMethod {
 - (void)testSwizzlingSuperclassInstanceMethod {
   NSObject *generalObject = [[NSObject alloc] init];
   BOOL generalObjectIsProxyValue = [generalObject isProxy];
-  BOOL (^newImplementation)() = ^BOOL() {
+  BOOL (^newImplementation)(void) = ^BOOL() {
     return !generalObjectIsProxyValue;
   };
 
@@ -325,7 +325,7 @@ - (void)testSwizzlingSuperclassInstanceMethod {
 /** Tests swizzling a superclass's class method. */
 - (void)testSwizzlingSuperclassClassMethod {
   NSString *swizzledDescription = @"Swizzled class description";
-  NSString * (^newImplementation)() = ^NSString *() {
+  NSString * (^newImplementation)(void) = ^NSString *() {
     return swizzledDescription;
   };
 
@@ -344,7 +344,7 @@ - (void)testSwizzlingInstanceMethodThatCallsSuper {
   TestObject *testObject = [[TestObject alloc] init];
   NSString *originalDescription = [testObject description];
   NSString *swizzledDescription = [originalDescription stringByAppendingString:@"SWIZZLED!"];
-  NSString * (^newImplementation)() = ^NSString *() {
+  NSString * (^newImplementation)(void) = ^NSString *() {
     return swizzledDescription;
   };
 
@@ -492,7 +492,7 @@ - (void)testSwizzlingInstanceMethodIsEffectiveOnMultipleInstancesOfSameClass {
 - (void)testSwizzlingClassMethodThatCallsSuper {
   NSString *originalDescription = [TestObject description];
   NSString *swizzledDescription = @"Swizzled class description";
-  NSString * (^newImplementation)() = ^NSString *() {
+  NSString * (^newImplementation)(void) = ^NSString *() {
     return swizzledDescription;
   };
 
@@ -513,7 +513,7 @@ - (void)testSwizzlingClassMethodThatCallsSuper {
 - (void)testSwizzlingAnInheritedInstanceMethodDoesntAffectTheIMPOfItsSuperclass {
   NSObject *generalObject = [[NSObject alloc] init];
   BOOL originalGeneralObjectValue = [generalObject isProxy];
-  BOOL (^newImplementation)() = ^BOOL() {
+  BOOL (^newImplementation)(void) = ^BOOL(void) {
     return !originalGeneralObjectValue;
   };
 
@@ -533,7 +533,7 @@ - (void)testSwizzlingAnInheritedInstanceMethodDoesntAffectTheIMPOfItsSuperclass
 - (void)testSwizzlingADeeperInheritedInstanceMethodDoesntAffectTheIMPOfItsSuperclass {
   TestObject *testObject = [[TestObject alloc] init];
   BOOL originalTestObjectValue = [testObject isProxy];
-  BOOL (^newImplementation)() = ^BOOL() {
+  BOOL (^newImplementation)(void) = ^BOOL(void) {
     return !originalTestObjectValue;
   };
 
@@ -556,7 +556,7 @@ - (void)testSwizzlingAnInheritedClassMethodDoesntAffectTheIMPOfItsSuperclass {
   // Fun fact, this won't work on +new. Swizzling +new causes a retain to not be placed correctly.
   NSString *originalDescription = [TestObject description];
   NSString *swizzledDescription = [originalDescription stringByAppendingString:@"SWIZZLED!"];
-  NSString * (^newImplementation)() = ^NSString *() {
+  NSString * (^newImplementation)(void) = ^NSString *() {
     return swizzledDescription;
   };
 
@@ -579,7 +579,7 @@ - (void)testSwizzlingAnInheritedClassMethodDoesntAffectTheIMPOfItsSuperclass {
 - (void)testSwizzlingADeeperInheritedClassMethodDoesntAffectTheIMPOfItsSuperclass {
   NSString *originalDescription = [TestObjectSubclass description];
   NSString *swizzledDescription = [originalDescription stringByAppendingString:@"SWIZZLED!"];
-  NSString * (^newImplementation)() = ^NSString *() {
+  NSString * (^newImplementation)(void) = ^NSString *() {
     return swizzledDescription;
   };