diff --git a/sources/src/main/java/io/akarin/api/internal/Akari.java b/sources/src/main/java/io/akarin/api/internal/Akari.java
index 245b93523..a4f7994b4 100644
--- a/sources/src/main/java/io/akarin/api/internal/Akari.java
+++ b/sources/src/main/java/io/akarin/api/internal/Akari.java
@@ -55,8 +55,12 @@ public abstract class Akari {
     public static final ExecutorCompletionService<?> STAGE_TICK = new ExecutorCompletionService<>(Executors.newSingleThreadExecutor(new AssignableFactory()));
     
     public static boolean isPrimaryThread() {
+        return isPrimaryThread(true);
+    }
+    
+    public static boolean isPrimaryThread(boolean assign) {
         Thread current = Thread.currentThread();
-        return current == MinecraftServer.getServer().primaryThread || current instanceof AssignableThread;
+        return current == MinecraftServer.getServer().primaryThread || (assign ? current instanceof AssignableThread : false);
     }
     
     public static final String EMPTY_STRING = "";
diff --git a/sources/src/main/java/io/akarin/server/mixin/core/MixinTimingHandler.java b/sources/src/main/java/io/akarin/server/mixin/core/MixinTimingHandler.java
index cb834a8ed..3fede2c32 100644
--- a/sources/src/main/java/io/akarin/server/mixin/core/MixinTimingHandler.java
+++ b/sources/src/main/java/io/akarin/server/mixin/core/MixinTimingHandler.java
@@ -27,7 +27,7 @@ public abstract class MixinTimingHandler {
     
     @Overwrite
     public Timing startTimingIfSync() {
-        if (Akari.isPrimaryThread()) { // Use non-mock method
+        if (Akari.isPrimaryThread(false)) { // Use non-mock method
             startTiming();
         }
         return (Timing) this;
@@ -36,12 +36,12 @@ public abstract class MixinTimingHandler {
     @SuppressWarnings({ "rawtypes", "unchecked" })
     @Inject(method = "startTiming", at = @At("HEAD"), cancellable = true)
     public void onStartTiming(CallbackInfoReturnable ci) {
-        if (!Akari.isPrimaryThread()) ci.setReturnValue(this); // Avoid modify any field
+        if (!Akari.isPrimaryThread(false)) ci.setReturnValue(this); // Avoid modify any field
     }
     
     @Overwrite
     public void stopTimingIfSync() {
-        if (Akari.isPrimaryThread()) {
+        if (Akari.isPrimaryThread(false)) {
             stopTiming(true); // Avoid twice thread check
         }
     }
@@ -53,7 +53,7 @@ public abstract class MixinTimingHandler {
     
     public void stopTiming(boolean alreadySync) {
         if (!enabled) return;
-        if (!alreadySync && !Akari.isPrimaryThread()) {
+        if (!alreadySync && !Akari.isPrimaryThread(false)) {
             if (AkarinGlobalConfig.silentAsyncTimings) return;
             
             Bukkit.getLogger().log(Level.SEVERE, "stopTiming called async for " + name);