@@ -16,10 +16,12 @@
 
 #import "OFObject.h"
 #import "OFString.h"
 #import "OFXMLAttribute.h"
 
+OF_ASSUME_NONNULL_BEGIN
+
 @class OFXMLParser;
 #ifndef DOXYGEN
 @class OFArray OF_GENERIC(ObjectType);
 @class OFMutableArray OF_GENERIC(ObjectType);
 @class OFMutableDictionary OF_GENERIC(KeyType, ObjectType);
@@ -57,13 +59,13 @@
  * @param attributes The attributes included in the tag which just started or
  *		     nil
  */
 -    (void)parser: (OFXMLParser*)parser
   didStartElement: (OFString*)name
-	   prefix: (OFString*)prefix
-	namespace: (OFString*)ns
-       attributes: (OFArray OF_GENERIC(OFXMLAttribute*)*)attributes;
+	   prefix: (nullable OFString*)prefix
+	namespace: (nullable OFString*)ns
+       attributes: (nullable OFArray OF_GENERIC(OFXMLAttribute*)*)attributes;
 
 /*!
  * @brief This callback is called when the XML parser found the end of a tag.
  *
  * @param parser The parser which found the end of a tag
@@ -71,12 +73,12 @@
  * @param prefix The prefix of the tag which just ended or nil
  * @param ns The namespace of the tag which just ended or nil
  */
 -  (void)parser: (OFXMLParser*)parser
   didEndElement: (OFString*)name
-	 prefix: (OFString*)prefix
-      namespace: (OFString*)ns;
+	 prefix: (nullable OFString*)prefix
+      namespace: (nullable OFString*)ns;
 
 /*!
  * @brief This callback is called when the XML parser found characters.
  *
  * In case there are comments or CDATA, it is possible that this callback is
@@ -174,11 +176,11 @@
 	of_string_encoding_t _encoding;
 	size_t _depthLimit;
 }
 
 #ifdef OF_HAVE_PROPERTIES
-@property (assign) id <OFXMLParserDelegate> delegate;
+@property (assign, nullable) id <OFXMLParserDelegate> delegate;
 @property size_t depthLimit;
 #endif
 
 /*!
  * @brief Creates a new XML parser.
@@ -185,23 +187,23 @@
  *
  * @return A new, autoreleased OFXMLParser
  */
 + (instancetype)parser;
 
-/*!
- * @brief Returns the delegate that is used by the XML parser.
- *
- * @return The delegate that is used by the XML parser
- */
-- (id <OFXMLParserDelegate>)delegate;
-
 /*!
  * @brief Sets the delegate the XML parser should use.
  *
  * @param delegate The delegate to use
  */
-- (void)setDelegate: (id <OFXMLParserDelegate>)delegate;
+- (void)setDelegate: (nullable id <OFXMLParserDelegate>)delegate;
+
+/*!
+ * @brief Returns the delegate that is used by the XML parser.
+ *
+ * @return The delegate that is used by the XML parser
+ */
+- (nullable id <OFXMLParserDelegate>)delegate;
 
 /*!
  * @brief Returns the depth limit for the XML parser.
  *
  * @return The depth limit for the XML parser
@@ -266,5 +268,7 @@
 - (bool)finishedParsing;
 @end
 
 @interface OFObject (OFXMLParserDelegate) <OFXMLParserDelegate>
 @end
+
+OF_ASSUME_NONNULL_END