@@ -18,17 +18,16 @@
 
 #include <stdlib.h>
 
 #import "OFHashAlreadyCalculatedException.h"
 #import "OFString.h"
-#import "OFHash.h"
 
 #import "common.h"
 
 @implementation OFHashAlreadyCalculatedException
 + (instancetype)exceptionWithClass: (Class)class
-			      hash: (OFHash*)hash
+			      hash: (id <OFHash>)hash
 {
 	return [[[self alloc] initWithClass: class
 				       hash: hash] autorelease];
 }
 
@@ -43,11 +42,11 @@
 
 	abort();
 }
 
 - initWithClass: (Class)class
-	   hash: (OFHash*)hashObject
+	   hash: (id <OFHash>)hashObject
 {
 	self = [super initWithClass: class];
 
 	_hashObject = [hashObject retain];
 
@@ -66,10 +65,10 @@
 	return [OFString stringWithFormat:
 	    @"The hash has already been calculated in class %@ and thus no new "
 	    @"data can be added", _inClass];
 }
 
-- (OFHash*)hashObject
+- (id <OFHash>)hashObject
 {
 	OF_GETTER(_hashObject, NO)
 }
 @end