Index: src/OFSerialization.m
==================================================================
--- src/OFSerialization.m
+++ src/OFSerialization.m
@@ -12,8 +12,9 @@
  * LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
  * file.
  */
 
 #import "OFSerialization.h"
+#import "OFString.h"
 
 OFConstantString *const OFSerializationNS =
     @"https://objfw.nil.im/serialization";