Index: src/OFValue.h
==================================================================
--- src/OFValue.h
+++ src/OFValue.h
@@ -22,11 +22,11 @@
 /*!
  * @class OFValue OFValue.h ObjFW/OFValue.h
  *
  * @brief A class for storing arbitrary values in an object.
  */
-@interface OFValue: OFObject
+@interface OFValue: OFObject <OFCopying>
 /*!
  * @brief The ObjC type encoding of the value.
  */
 @property (readonly, nonatomic) const char *objCType;
 

Index: src/OFValue.m
==================================================================
--- src/OFValue.m
+++ src/OFValue.m
@@ -162,10 +162,15 @@
 		free(buffer);
 	}
 
 	return hash;
 }
+
+- (id)copy
+{
+	return [self retain];
+}
 
 - (const char *)objCType
 {
 	OF_UNRECOGNIZED_SELECTOR
 }