diff --git a/GoogleSignIn/Tests/Unit/GIDGoogleUserTest.m b/GoogleSignIn/Tests/Unit/GIDGoogleUserTest.m
index 1410ce74..1199fc48 100644
--- a/GoogleSignIn/Tests/Unit/GIDGoogleUserTest.m
+++ b/GoogleSignIn/Tests/Unit/GIDGoogleUserTest.m
@@ -39,9 +39,8 @@
 static NSString *const kNewRefreshToken = @"new_refresh_token";
 
 static NSTimeInterval const kTimeAccuracy = 10;
-// The difference between times.
-// It should be larger than kTimeAccuracy which is used in the method `XCTAssertEqualWithAccuracy`.
-static NSTimeInterval const kTimeIncrement = 100;
+static NSTimeInterval const kIDTokenExpiresIn = 100;
+static NSTimeInterval const kNewIDTokenExpiresIn = 200;
 
 @interface GIDGoogleUserTest : XCTestCase
 @end
@@ -101,43 +100,40 @@ - (void)testLegacyCoding {
 #endif // TARGET_OS_IOS || TARGET_OS_MACCATALYST
 
 - (void)testUpdateAuthState {
-  NSTimeInterval accessTokenExpireTime = [[NSDate date] timeIntervalSince1970];
-  NSTimeInterval idTokenExpireTime = accessTokenExpireTime + kTimeIncrement;
+  GIDGoogleUser *user = [self googleUserWithAccessTokenExpiresIn:kAccessTokenExpiresIn
+                                                idTokenExpiresIn:kIDTokenExpiresIn];
   
-  GIDGoogleUser *user = [self googleUserWithAccessTokenExpireTime:accessTokenExpireTime
-                                                idTokenExpireTime:idTokenExpireTime];
-  
-  NSTimeInterval updatedAccessTokenExpireTime = idTokenExpireTime + kTimeIncrement;
-  NSTimeInterval updatedIDTokenExpireTime = updatedAccessTokenExpireTime + kTimeIncrement;
-  NSString *updatedIDToken = [self idTokenWithExpireTime:updatedIDTokenExpireTime];
+  NSString *updatedIDToken = [self idTokenWithExpiresIn:kNewIDTokenExpiresIn];
   OIDAuthState *updatedAuthState = [OIDAuthState testInstanceWithIDToken:updatedIDToken
                                                              accessToken:kNewAccessToken
-                                                   accessTokenExpireTime:updatedAccessTokenExpireTime
+                                                    accessTokenExpiresIn:kAccessTokenExpiresIn
                                                             refreshToken:kNewRefreshToken];
   GIDProfileData *updatedProfileData = [GIDProfileData testInstance];
   
   [user updateAuthState:updatedAuthState profileData:updatedProfileData];
   
   XCTAssertEqualObjects(user.accessToken.tokenString, kNewAccessToken);
+  NSDate *expectedAccessTokenExpirationDate = [[NSDate date] dateByAddingTimeInterval:kAccessTokenExpiresIn];
   XCTAssertEqualWithAccuracy([user.accessToken.expirationDate timeIntervalSince1970],
-                             updatedAccessTokenExpireTime, kTimeAccuracy);
+                             [expectedAccessTokenExpirationDate timeIntervalSince1970], kTimeAccuracy);
+  
   XCTAssertEqualObjects(user.idToken.tokenString, updatedIDToken);
+  NSDate *expectedIDTokenExpirationDate = [[NSDate date] dateByAddingTimeInterval:kNewIDTokenExpiresIn];
   XCTAssertEqualWithAccuracy([user.idToken.expirationDate timeIntervalSince1970],
-                             updatedIDTokenExpireTime, kTimeAccuracy);
+                             [expectedIDTokenExpirationDate timeIntervalSince1970], kTimeAccuracy);
+  
   XCTAssertEqualObjects(user.refreshToken.tokenString, kNewRefreshToken);
+  
   XCTAssertEqual(user.profile, updatedProfileData);
 }
 
 // When updating with a new OIDAuthState in which token information is not changed, the token objects
 // should remain the same.
 - (void)testUpdateAuthState_tokensAreNotChanged {
-  NSTimeInterval accessTokenExpireTime = [[NSDate date] timeIntervalSince1970];
-  NSTimeInterval idTokenExpireTime = [[NSDate date] timeIntervalSince1970];
-  
-  NSString *idToken = [self idTokenWithExpireTime:idTokenExpireTime];
+  NSString *idToken = [self idTokenWithExpiresIn:kIDTokenExpiresIn];
   OIDAuthState *authState = [OIDAuthState testInstanceWithIDToken:idToken
                                                       accessToken:kAccessToken
-                                            accessTokenExpireTime:accessTokenExpireTime
+                                             accessTokenExpiresIn:kAccessTokenExpiresIn
                                                      refreshToken:kRefreshToken];
   
   GIDGoogleUser *user = [[GIDGoogleUser alloc] initWithAuthState:authState profileData:nil];
@@ -155,19 +151,20 @@ - (void)testUpdateAuthState_tokensAreNotChanged {
 
 #pragma mark - Helpers
 
-- (GIDGoogleUser *)googleUserWithAccessTokenExpireTime:(NSTimeInterval)accessTokenExpireTime
-                                     idTokenExpireTime:(NSTimeInterval)idTokenExpireTime {
-  NSString *idToken = [self idTokenWithExpireTime:idTokenExpireTime];
+- (GIDGoogleUser *)googleUserWithAccessTokenExpiresIn:(NSTimeInterval)accessTokenExpiresIn
+                                     idTokenExpiresIn:(NSTimeInterval)idTokenExpiresIn {
+  NSString *idToken = [self idTokenWithExpiresIn:idTokenExpiresIn];
   OIDAuthState *authState = [OIDAuthState testInstanceWithIDToken:idToken
                                                       accessToken:kAccessToken
-                                            accessTokenExpireTime:accessTokenExpireTime
+                                             accessTokenExpiresIn:accessTokenExpiresIn
                                                      refreshToken:kRefreshToken];
   
   return [[GIDGoogleUser alloc] initWithAuthState:authState profileData:nil];
 }
 
-// The expireTime should be based on 1970.
-- (NSString *)idTokenWithExpireTime:(NSTimeInterval)expireTime {
+- (NSString *)idTokenWithExpiresIn:(NSTimeInterval)expiresIn {
+  // The expireTime should be based on 1970.
+  NSTimeInterval expireTime = [[NSDate date] timeIntervalSince1970] + expiresIn;
   return [OIDTokenResponse idTokenWithSub:kUserID exp:@(expireTime)];
 }
 
diff --git a/GoogleSignIn/Tests/Unit/OIDAuthState+Testing.h b/GoogleSignIn/Tests/Unit/OIDAuthState+Testing.h
index f660e34e..15feb758 100644
--- a/GoogleSignIn/Tests/Unit/OIDAuthState+Testing.h
+++ b/GoogleSignIn/Tests/Unit/OIDAuthState+Testing.h
@@ -28,9 +28,15 @@
 
 + (instancetype)testInstanceWithTokenResponse:(OIDTokenResponse *)tokenResponse;
 
+/**
+ * @idToken The ID token.
+ * @accessToken The access token string.
+ * @accessTokenExipresIn The life time of the access token starting from the moment when `OIDTokenResponse` is created.
+ * @refreshToken The refresh token string.
+ */
 + (instancetype)testInstanceWithIDToken:(NSString *)idToken
                             accessToken:(NSString *)accessToken
-                  accessTokenExpireTime:(NSTimeInterval)accessTokenExpireTime
+                   accessTokenExpiresIn:(NSTimeInterval)accessTokenExpiresIn
                            refreshToken:(NSString *)refreshToken;
 
 @end
diff --git a/GoogleSignIn/Tests/Unit/OIDAuthState+Testing.m b/GoogleSignIn/Tests/Unit/OIDAuthState+Testing.m
index b9082227..c6c694a4 100644
--- a/GoogleSignIn/Tests/Unit/OIDAuthState+Testing.m
+++ b/GoogleSignIn/Tests/Unit/OIDAuthState+Testing.m
@@ -35,14 +35,12 @@ + (instancetype)testInstanceWithTokenResponse:(OIDTokenResponse *)tokenResponse
 
 + (instancetype)testInstanceWithIDToken:(NSString *)idToken
                             accessToken:(NSString *)accessToken
-                  accessTokenExpireTime:(NSTimeInterval)accessTokenExpireTime
+                   accessTokenExpiresIn:(NSTimeInterval)accessTokenExpiresIn
                            refreshToken:(NSString *)refreshToken {
-  NSNumber *accessTokenExpiresIn =
-      @(accessTokenExpireTime - [[NSDate date] timeIntervalSince1970]);
   OIDTokenResponse *newResponse =
       [OIDTokenResponse testInstanceWithIDToken:idToken
                                     accessToken:accessToken
-                                      expiresIn:accessTokenExpiresIn
+                                      expiresIn:@(accessTokenExpiresIn)
                                    refreshToken:refreshToken
                                    tokenRequest:nil];
   return [self testInstanceWithTokenResponse:newResponse];