@@ -18,10 +18,12 @@
 
 #ifdef OF_HAVE_THREADS
 # import "threading.h"
 #endif
 
+OF_ASSUME_NONNULL_BEGIN
+
 /*! @file */
 
 @class OFDate;
 @class OFRunLoop;
 @class OFMutableDictionary OF_GENERIC(KeyType, ObjectType);
@@ -30,11 +32,11 @@
 /*!
  * @brief A block to be executed in a new thread.
  *
  * @return The object which should be returned when the thread is joined
  */
-typedef id (^of_thread_block_t)(void);
+typedef __nullable id (^of_thread_block_t)(void);
 #endif
 
 /*!
  * @class OFThread OFThread.h ObjFW/OFThread.h
  *
@@ -154,11 +156,11 @@
 /*!
  * @brief Terminates the current thread, letting it return the specified object.
  *
  * @param object The object which the terminated thread will return
  */
-+ (void)terminateWithObject: (id)object OF_NO_RETURN;
++ (void)terminateWithObject: (nullable id)object OF_NO_RETURN;
 
 # ifdef OF_HAVE_BLOCKS
 /*!
  * @brief Initializes an already allocated thread with the specified block.
  *
@@ -174,11 +176,11 @@
  * It can access the object passed to the threadWithObject or initWithObject
  * method using the instance variable named object.
  *
  * @return The object the join method should return when called for this thread
  */
-- (id)main;
+- (nullable id)main;
 
 /*!
  * @brief This routine is exectued when the thread's main method has finished
  *	  executing or terminate has been called.
  *
@@ -208,18 +210,18 @@
 /*!
  * @brief Returns the name of the thread or nil if none has been set.
  *
  * @return The name of the thread or nik if none has been set
  */
-- (OFString*)name;
+- (nullable OFString*)name;
 
 /*!
  * @brief Sets the name for the thread.
  *
  * @param name The name for the thread
  */
-- (void)setName: (OFString*)name;
+- (void)setName: (nullable OFString*)name;
 
 /*!
  * @brief Returns the priority of the thread.
  *
  * @return The priority of the thread
@@ -251,5 +253,7 @@
  * @param stackSize The stack size for the thread
  */
 - (void)setStackSize: (size_t)stackSize;
 #endif
 @end
+
+OF_ASSUME_NONNULL_END