diff --git a/backends/playback/zsm/zsm_backend.cpp b/backends/playback/zsm/zsm_backend.cpp
index e41807b..394ac77 100644
--- a/backends/playback/zsm/zsm_backend.cpp
+++ b/backends/playback/zsm/zsm_backend.cpp
@@ -132,7 +132,6 @@ void ZsmBackend::tick(bool step) {
                     while (YM_read_status()) {
                         size_t clocksToAddForYm = 64;
                         ticks_remaining -= clocksToAddForYm;
-                        prevCpuClocks += clocksToAddForYm;
                         if (ticks_remaining < 0) {
                             delayTicks -= 1;
                             nextCpuClocks += ClocksPerTick;
@@ -211,7 +210,7 @@ void ZsmBackend::tick(bool step) {
     size_t nextCpuClocksInt = std::floor(nextCpuClocks);
     size_t prevCpuClocksInt = std::floor(prevCpuClocks);
     size_t cpuClocksIntDelta = nextCpuClocksInt - prevCpuClocksInt;
-    audio_step(cpuClocksIntDelta);
+    audio_step(ticks_remaining);
     cpuClocks = std::fmod(nextCpuClocks, ClocksPerTick);
 }
 size_t ZsmBackend::render(void *buf, size_t maxlen) {