@@ -40,11 +40,11 @@
 {
 	self = [super init];
 
 	@try {
 		void *pool = objc_autoreleasePoolPush();
-		size_t numberOfArguments = [signature numberOfArguments];
+		size_t numberOfArguments = signature.numberOfArguments;
 		const char *typeEncoding;
 		size_t typeSize;
 
 		_methodSignature = [signature retain];
 		_arguments = [[OFMutableArray alloc] init];
@@ -60,11 +60,11 @@
 						      capacity: 1];
 			[data increaseCountBy: 1];
 			[_arguments addObject: data];
 		}
 
-		typeEncoding = [_methodSignature methodReturnType];
+		typeEncoding = _methodSignature.methodReturnType;
 		typeSize = of_sizeof_type_encoding(typeEncoding);
 
 		if (typeSize > 0) {
 			_returnValue = [[OFMutableData alloc]
 			    initWithItemSize: typeSize
@@ -93,33 +93,33 @@
 - (void)setArgument: (const void *)buffer
 	    atIndex: (size_t)idx
 {
 	OFMutableData *data = [_arguments objectAtIndex: idx];
 
-	memcpy([data items], buffer, [data itemSize]);
+	memcpy(data.mutableItems, buffer, data.itemSize);
 }
 
 - (void)getArgument: (void *)buffer
 	    atIndex: (size_t)idx
 {
 	OFData *data = [_arguments objectAtIndex: idx];
 
-	memcpy(buffer, [data items], [data itemSize]);
+	memcpy(buffer, data.items, data.itemSize);
 }
 
 - (void)setReturnValue: (const void *)buffer
 {
-	memcpy([_returnValue items], buffer, [_returnValue itemSize]);
+	memcpy(_returnValue.mutableItems, buffer, _returnValue.itemSize);
 }
 
 - (void)getReturnValue: (void *)buffer
 {
-	memcpy(buffer, [_returnValue items], [_returnValue itemSize]);
+	memcpy(buffer, _returnValue.items, _returnValue.itemSize);
 }
 
 #ifdef OF_INVOCATION_CAN_INVOKE
 - (void)invoke
 {
 	of_invocation_invoke(self);
 }
 #endif
 @end