@@ -14,10 +14,12 @@
  * file.
  */
 
 #import "OFObject.h"
 #import "OFXMLParser.h"
+
+OF_ASSUME_NONNULL_BEGIN
 
 @class OFMutableArray OF_GENERIC(ObjectType);
 @class OFXMLElement;
 @class OFXMLElementBuilder;
 
@@ -77,12 +79,12 @@
  * @param prefix The prefix of the close tag
  * @param namespace_ The namespace of the close tag
  */
 - (void)elementBuilder: (OFXMLElementBuilder*)builder
   didNotExpectCloseTag: (OFString*)name
-		prefix: (OFString*)prefix
-	     namespace: (OFString*)namespace_;
+		prefix: (nullable OFString*)prefix
+	     namespace: (nullable OFString*)namespace_;
 
 /*!
  * @brief This callback is called when the XML parser for the element builder
  *	  found an unknown entity.
  *
@@ -109,32 +111,34 @@
 	OFMutableArray OF_GENERIC(OFXMLElement*) *_stack;
 	id <OFXMLElementBuilderDelegate> _delegate;
 }
 
 #ifdef OF_HAVE_PROPERTIES
-@property (assign) id <OFXMLElementBuilderDelegate> delegate;
+@property (assign, nullable) id <OFXMLElementBuilderDelegate> delegate;
 #endif
 
 /*!
  * @brief Creates a new element builder.
  *
  * @return A new, autoreleased OFXMLElementBuilder
  */
 + (instancetype)elementBuilder;
 
-/*!
- * @brief Returns the delegate for the OFXMLElementBuilder.
- *
- * @return The delegate for the OFXMLElementBuilder
- */
-- (id <OFXMLElementBuilderDelegate>)delegate;
-
 /*!
  * @brief Sets the delegate for the OFXMLElementBuilder.
  *
  * @param delegate The delegate for the OFXMLElementBuilder
  */
-- (void)setDelegate: (id <OFXMLElementBuilderDelegate>)delegate;
+- (void)setDelegate: (nullable id <OFXMLElementBuilderDelegate>)delegate;
+
+/*!
+ * @brief Returns the delegate for the OFXMLElementBuilder.
+ *
+ * @return The delegate for the OFXMLElementBuilder
+ */
+- (nullable id <OFXMLElementBuilderDelegate>)delegate;
 @end
 
 @interface OFObject (OFXMLElementBuilderDelegate) <OFXMLElementBuilderDelegate>
 @end
+
+OF_ASSUME_NONNULL_END