A method for using a retain block in application code executing on a virtual machine includes identifying an instruction in application code, the instruction pertaining to an object, determining the instruction is part of a retain block, prior to executing the instruction, determining whether the instruction is to cause the object to be modified, and when the instruction is to cause the object to be modified, storing data indicating a first state of the object in a retain block store and causing the first state of the object to be modified using a second state. Also, the method includes in response to an error occurring during an execution of the instruction, returning the object from the second state to the first state using the stored data.