diff --git a/changelog.md b/changelog.md
index 7e632aa..24dcdb2 100644
--- a/changelog.md
+++ b/changelog.md
@@ -23,6 +23,7 @@ These changes will (most likely) be included in the next version.
 - The new command `/ma ready` (`/ma rdy` for short) can be used as an alternative to the iron block for readying up.  
 - Total experience is now correctly stored, reset, and restored on arena join/leave. This fixes a potential bug where total experience could increase in the arena, but levels and progress would still get reset at arena end.
 - The per-arena setting `keep-exp` returns. If enabled, any experience collected during an arena session is added as a reward on death or when the final wave is reached.
+- Waves will no longer intermittently progress at double frequency in some arena sessions. This long-standing bug where waves progress at "double speed" has finally been fixed.
 
 Thanks to:
 - Sait for adding the /ma ready command
diff --git a/src/main/java/com/garbagemule/MobArena/ArenaImpl.java b/src/main/java/com/garbagemule/MobArena/ArenaImpl.java
index a320b97..88329ef 100644
--- a/src/main/java/com/garbagemule/MobArena/ArenaImpl.java
+++ b/src/main/java/com/garbagemule/MobArena/ArenaImpl.java
@@ -996,26 +996,15 @@ public class ArenaImpl implements Arena
     }
     
     private void startSpawner() {
-        // Set the spawn flags to enable monster spawning.
-        world.setSpawnFlags(true, true);
-        //world.setDifficulty(Difficulty.NORMAL);
-        
-        // Create a spawner if one doesn't exist, otherwise reset it
-        if (spawnThread == null) {
-            spawnThread  = new MASpawnThread(plugin, this);
-        } else {
-            spawnThread.reset();
+        if (spawnThread != null) {
+            spawnThread.stop();
+            spawnThread = null;
         }
-        
-        // Schedule it for the initial first wave delay.
-        scheduleTask(spawnThread, settings.getInt("first-wave-delay", 5) * 20);
-        
-        // Schedule to enable PvP if pvp-enabled: true
-        scheduleTask(new Runnable() {
-            public void run() {
-                eventListener.pvpActivate();
-            }
-        }, settings.getInt("first-wave-delay", 5) * 20);
+
+        world.setSpawnFlags(true, true);
+
+        spawnThread = new MASpawnThread(plugin, this);
+        spawnThread.start();
     }
     
     /**
@@ -1030,9 +1019,15 @@ public class ArenaImpl implements Arena
     }
     
     private void stopSpawner() {
+        if (spawnThread == null) {
+            plugin.getLogger().warning("Can't stop non-existent spawner in arena " + configName() + ". This should never happen.");
+            return;
+        }
+
+        spawnThread.stop();
+        spawnThread = null;
+
         world.setSpawnFlags(allowMonsters, allowAnimals);
-        eventListener.pvpDeactivate();
-        //world.setDifficulty(spawnMonsters);
     }
     
     private void startBouncingSheep()
diff --git a/src/main/java/com/garbagemule/MobArena/MASpawnThread.java b/src/main/java/com/garbagemule/MobArena/MASpawnThread.java
index 947cbb7..34a4b69 100644
--- a/src/main/java/com/garbagemule/MobArena/MASpawnThread.java
+++ b/src/main/java/com/garbagemule/MobArena/MASpawnThread.java
@@ -16,11 +16,13 @@ import com.garbagemule.MobArena.waves.enums.WaveType;
 import com.garbagemule.MobArena.waves.types.BossWave;
 import com.garbagemule.MobArena.waves.types.SupplyWave;
 import com.garbagemule.MobArena.waves.types.UpgradeWave;
+import org.bukkit.Bukkit;
 import org.bukkit.Location;
 import org.bukkit.World;
 import org.bukkit.entity.Entity;
 import org.bukkit.entity.LivingEntity;
 import org.bukkit.entity.Player;
+import org.bukkit.scheduler.BukkitTask;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -41,6 +43,8 @@ public class MASpawnThread implements Runnable
     private int waveInterval;
     private int nextWaveDelay;
 
+    private BukkitTask task;
+
     /**
      * Create a new monster spawner for the input arena.
      * Note that the arena's WaveManager is reset
@@ -75,6 +79,32 @@ public class MASpawnThread implements Runnable
         nextWaveDelay = arena.getSettings().getInt("next-wave-delay", 0);
     }
 
+    public void start() {
+        if (task != null) {
+            plugin.getLogger().warning("Starting spawner in arena " + arena.configName() + " with existing spawner still running. This should never happen.");
+            task.cancel();
+            task = null;
+        }
+
+        int delay = arena.getSettings().getInt("first-wave-delay", 5) * 20;
+        task = Bukkit.getScheduler().runTaskLater(plugin, () -> {
+            arena.getEventListener().pvpActivate();
+            this.run();
+        }, delay);
+    }
+
+    public void stop() {
+        if (task == null) {
+            plugin.getLogger().warning("Can't stop non-existent spawner in arena " + arena.configName() + ". This should never happen.");
+            return;
+        }
+
+        arena.getEventListener().pvpDeactivate();
+
+        task.cancel();
+        task = null;
+    }
+
     public void run() {
         // If the arena isn't running or if there are no players in it.
         if (!arena.isRunning() || arena.getPlayersInArena().isEmpty()) {
@@ -109,7 +139,7 @@ public class MASpawnThread implements Runnable
 
         // Delay the next wave
         if (nextWaveDelay > 0) {
-            arena.scheduleTask(this::spawnNextWave, nextWaveDelay * 20);
+            task = Bukkit.getScheduler().runTaskLater(plugin, this::spawnNextWave, nextWaveDelay * 20);
         } else {
             spawnNextWave();
         }
@@ -146,7 +176,7 @@ public class MASpawnThread implements Runnable
         updateStats(nextWave);
 
         // Reschedule the spawner for the next wave.
-        arena.scheduleTask(this, waveInterval * 20);
+        task = Bukkit.getScheduler().runTaskLater(plugin, this, waveInterval * 20);
     }
 
     private void spawnWave(int wave) {