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