@@ -16,10 +16,12 @@
 
 #import "OFObject.h"
 #import "OFCollection.h"
 #import "OFEnumerator.h"
 #import "OFSerialization.h"
+
+OF_ASSUME_NONNULL_BEGIN
 
 typedef struct of_list_object_t of_list_object_t;
 /*!
  * @struct of_list_object_t OFList.h ObjFW/OFList.h
  *
@@ -57,12 +59,12 @@
 	size_t		 _count;
 	unsigned long	 _mutations;
 }
 
 #ifdef OF_HAVE_PROPERTIES
-@property (readonly) of_list_object_t *firstListObject;
-@property (readonly) of_list_object_t *lastListObject;
+@property (readonly, nullable) of_list_object_t *firstListObject;
+@property (readonly, nullable) of_list_object_t *lastListObject;
 #endif
 
 /*!
  * @brief Creates a new OFList.
  *
@@ -73,18 +75,18 @@
 /*!
  * @brief Returns the first list object of the list.
  *
  * @return The first list object of the list
  */
-- (of_list_object_t*)firstListObject;
+- (nullable of_list_object_t*)firstListObject;
 
 /*!
  * @brief Returns the last list object of the list.
  *
  * @return The last list object of the list
  */
-- (of_list_object_t*)lastListObject;
+- (nullable of_list_object_t*)lastListObject;
 
 /*!
  * @brief Appends an object to the list.
  *
  * @param object The object to append
@@ -142,20 +144,20 @@
  *	  object.
  *
  * @param object The object which is checked for being in the list
  * @return A boolean whether the list contains the specified object
  */
-- (bool)containsObject: (ObjectType)object;
+- (bool)containsObject: (nullable ObjectType)object;
 
 /*!
  * @brief Checks whether the list contains an object with the specified address.
  *
  * @param object The object which is checked for being in the list
  * @return A boolean whether the list contains an object with the specified
  *	   address
  */
-- (bool)containsObjectIdenticalTo: (ObjectType)object;
+- (bool)containsObjectIdenticalTo: (nullable ObjectType)object;
 
 /*!
  * @brief Returns an OFEnumerator to enumerate through all objects of the list.
  *
  * @returns An OFEnumerator to enumerate through all objects of the list
@@ -168,21 +170,21 @@
  * @warning The returned object is *not* retained and autoreleased for
  *	    performance reasons!
  *
  * @return The first object of the list or nil
  */
-- (ObjectType)firstObject;
+- (nullable ObjectType)firstObject;
 
 /*!
  * @brief Returns the last object of the list or nil.
  *
  * @warning The returned object is *not* retained and autoreleased for
  *	    performance reasons!
  *
  * @return The last object of the list or nil
  */
-- (ObjectType)lastObject;
+- (nullable ObjectType)lastObject;
 
 /*!
  * @brief Removes all objects from the list.
  */
 - (void)removeAllObjects;
@@ -200,5 +202,7 @@
 }
 
 -     initWithList: (OFList*)list
   mutationsPointer: (unsigned long*)mutationsPtr;
 @end
+
+OF_ASSUME_NONNULL_END