diff --git a/Processors/Z80/Z80.hpp b/Processors/Z80/Z80.hpp
index d4c28c06a..ae162af93 100644
--- a/Processors/Z80/Z80.hpp
+++ b/Processors/Z80/Z80.hpp
@@ -538,7 +538,8 @@ template <class T> class Processor: public MicroOpScheduler<MicroOp> {
 						if(number_of_cycles_ < operation->machine_cycle.length) {
 							return;
 						}
-						static_cast<T *>(this)->perform_machine_cycle(&operation->machine_cycle);
+						number_of_cycles_ -= operation->machine_cycle.length;
+						number_of_cycles_ -= static_cast<T *>(this)->perform_machine_cycle(&operation->machine_cycle);
 					break;
 					case MicroOp::MoveToNextProgram:
 						move_to_next_program();