diff --git a/Source/AppAuthCore/OIDEndSessionRequest.h b/Source/AppAuthCore/OIDEndSessionRequest.h
index 4087e9fa9..22885e19b 100644
--- a/Source/AppAuthCore/OIDEndSessionRequest.h
+++ b/Source/AppAuthCore/OIDEndSessionRequest.h
@@ -75,8 +75,8 @@ NS_ASSUME_NONNULL_BEGIN
 */
 - (instancetype)
     initWithConfiguration:(OIDServiceConfiguration *)configuration
-              idTokenHint:(NSString *)idTokenHint
-    postLogoutRedirectURL:(NSURL *)postLogoutRedirectURL
+              idTokenHint:(nullable NSString *)idTokenHint
+    postLogoutRedirectURL:(nullable NSURL *)postLogoutRedirectURL
      additionalParameters:(nullable NSDictionary<NSString *, NSString *> *)additionalParameters;
 
 /*! @brief Designated initializer.
@@ -89,9 +89,9 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (instancetype)
     initWithConfiguration:(OIDServiceConfiguration *)configuration
-              idTokenHint:(NSString *)idTokenHint
-    postLogoutRedirectURL:(NSURL *)postLogoutRedirectURL
-                    state:(NSString *)state
+              idTokenHint:(nullable NSString *)idTokenHint
+    postLogoutRedirectURL:(nullable NSURL *)postLogoutRedirectURL
+                    state:(nullable NSString *)state
      additionalParameters:(nullable NSDictionary<NSString *, NSString *> *)additionalParameters
     NS_DESIGNATED_INITIALIZER;
 
diff --git a/Source/AppAuthCore/OIDEndSessionRequest.m b/Source/AppAuthCore/OIDEndSessionRequest.m
index 1e9eb0e22..25ee3f66e 100644
--- a/Source/AppAuthCore/OIDEndSessionRequest.m
+++ b/Source/AppAuthCore/OIDEndSessionRequest.m
@@ -64,9 +64,9 @@ - (instancetype)init
     )
 
 - (instancetype)initWithConfiguration:(OIDServiceConfiguration *)configuration
-                          idTokenHint:(NSString *)idTokenHint
-                postLogoutRedirectURL:(NSURL *)postLogoutRedirectURL
-                                state:(NSString *)state
+                          idTokenHint:(nullable NSString *)idTokenHint
+                postLogoutRedirectURL:(nullable NSURL *)postLogoutRedirectURL
+                                state:(nullable NSString *)state
                  additionalParameters:(NSDictionary<NSString *,NSString *> *)additionalParameters
 {
   self = [super init];
@@ -82,8 +82,8 @@ - (instancetype)initWithConfiguration:(OIDServiceConfiguration *)configuration
 }
 
 - (instancetype)initWithConfiguration:(OIDServiceConfiguration *)configuration
-                          idTokenHint:(NSString *)idTokenHint
-                postLogoutRedirectURL:(NSURL *)postLogoutRedirectURL
+                          idTokenHint:(nullable NSString *)idTokenHint
+                postLogoutRedirectURL:(nullable NSURL *)postLogoutRedirectURL
                  additionalParameters:(NSDictionary<NSString *,NSString *> *)additionalParameters
 {
   return [self initWithConfiguration:configuration