@@ -16,10 +16,12 @@
 
 #import <Foundation/NSString.h>
 
 #import "NSBridging.h"
 
+OF_ASSUME_NONNULL_BEGIN
+
 /*!
  * @category NSString (OFObject)
  *	     NSString+OFObject.h ObjFW-Bridge/NSString+OFObject.h
  *
  * @brief Support for bridging NSStrings to OFStrings.
@@ -28,5 +30,7 @@
  * handling UCS-4 properly (a character of NSString is only 2 bytes, while a
  * character of OFString is 4).
  */
 @interface NSString (OFObject) <NSBridging>
 @end
+
+OF_ASSUME_NONNULL_END