diff --git a/src/engine/sysDef.cpp b/src/engine/sysDef.cpp
index d7df4d805..17ab8cfc3 100644
--- a/src/engine/sysDef.cpp
+++ b/src/engine/sysDef.cpp
@@ -1649,7 +1649,7 @@ void DivEngine::registerSystems() {
     {0x1e, {DIV_CMD_SU_SYNC_PERIOD_LOW, "1Exx: Set phase reset period low byte"}},
     {0x1f, {DIV_CMD_SU_SYNC_PERIOD_HIGH, "1Fxx: Set phase reset period high byte"}},
     {0x20, {DIV_CMD_SU_SWEEP_ENABLE, "20xx: Toggle frequency sweep (bit 0-6: speed; bit 7: direction is up)", constVal<0>, effectVal}},
-    {0x21, {DIV_CMD_SU_SWEEP_ENABLE, "21xx: Toggle volume sweep (bit 0-4: speed; bit 5: direciton is up; bit 6: loop; bit 7: alternate)", constVal<1>, effectVal}},
+    {0x21, {DIV_CMD_SU_SWEEP_ENABLE, "21xx: Toggle volume sweep (bit 0-4: speed; bit 5: direction is up; bit 6: loop; bit 7: alternate)", constVal<1>, effectVal}},
     {0x22, {DIV_CMD_SU_SWEEP_ENABLE, "22xx: Toggle cutoff sweep (bit 0-6: speed; bit 7: direction is up)", constVal<2>, effectVal}},
   };
   const EffectHandler suCutoffHandler(DIV_CMD_C64_FINE_CUTOFF, "4xxx: Set cutoff (0 to FFF)", effectValLong<12>);