Index: src/OFApplication.h
==================================================================
--- src/OFApplication.h
+++ src/OFApplication.h
@@ -156,32 +156,32 @@
 /*!
  * @brief Returns the only OFApplication instance in the application.
  *
  * @return The only OFApplication instance in the application
  */
-+ (OFApplication *)sharedApplication;
++ (nullable OFApplication *)sharedApplication;
 
 /*!
  * @brief Returns the name of the program (argv[0]).
  *
  * @return The name of the program (argv[0])
  */
-+ (OFString *)programName;
++ (nullable OFString *)programName;
 
 /*!
  * @brief Returns the arguments passed to the application.
  *
  * @return The arguments passed to the application
  */
-+ (OFArray OF_GENERIC(OFString *) *)arguments;
++ (nullable OFArray OF_GENERIC(OFString *) *)arguments;
 
 /*!
  * @brief Returns the environment of the application.
  *
  * @return The environment of the application
  */
-+ (OFDictionary OF_GENERIC(OFString *, OFString *) *)environment;
++ (nullable OFDictionary OF_GENERIC(OFString *, OFString *) *)environment;
 
 /*!
  * @brief Terminates the application with the EXIT_SUCCESS status.
  */
 + (void)terminate OF_NO_RETURN;

Index: src/OFArray.h
==================================================================
--- src/OFArray.h
+++ src/OFArray.h
@@ -513,11 +513,11 @@
 	unsigned long *_Nullable _mutationsPtr;
 	size_t _position;
 }
 
 - initWithArray: (OFArray *)data
-   mutationsPtr: (unsigned long *_Nullable)mutationsPtr;
+   mutationsPtr: (nullable unsigned long *)mutationsPtr;
 @end
 
 OF_ASSUME_NONNULL_END
 
 #import "OFMutableArray.h"

Index: src/OFConstantString.m
==================================================================
--- src/OFConstantString.m
+++ src/OFConstantString.m
@@ -113,11 +113,11 @@
 {
 #if defined(OF_APPLE_RUNTIME) && !defined(__OBJC2__)
 	/*
 	 * objc_setFutureClass suddenly stopped working as OFConstantString
 	 * became more complex. So the only solution is to make
-	 * _OFConstantStringClassRerence the actual class, but there is no
+	 * _OFConstantStringClassReference the actual class, but there is no
 	 * objc_initializeClassPair in 10.5. However, objc_allocateClassPair
 	 * does not register the new class with the subclass in the ObjC1
 	 * runtime like the ObjC2 runtime does, so this workaround should be
 	 * fine.
 	 */

Index: src/OFUDPSocket.h
==================================================================
--- src/OFUDPSocket.h
+++ src/OFUDPSocket.h
@@ -179,11 +179,11 @@
  * @param port A pointer to an uint16_t. If it is not NULL, the port of the
  *	       host / port pair will be written to it.
  * @param address The address for which the host and port should be retrieved
  */
 + (void)getHost: (OFString *__autoreleasing _Nonnull *_Nullable)host
-	andPort: (uint16_t *_Nullable)port
+	andPort: (nullable uint16_t *)port
      forAddress: (of_udp_socket_address_t *)address;
 
 /*!
  * @brief Binds the socket to the specified host and port.
  *