diff --git a/LICENSE b/LICENSE
index 3d8a2c7a..1af01810 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2019 Kotlin Android Open Source
+Copyright (c) 2019-2021 Kotlin Android Open Source
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index 1c27ad9f..f73e6abe 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -67,6 +67,7 @@ dependencies {
   implementation(deps.koin.android)
 
   debugImplementation(deps.squareup.leakCanary)
+  implementation(deps.timber)
 
   testImplementation(deps.test.junit)
   androidTestImplementation(deps.test.androidxJunit)
diff --git a/app/src/main/java/com/hoc/flowmvi/App.kt b/app/src/main/java/com/hoc/flowmvi/App.kt
index 2061ce47..f703fc24 100644
--- a/app/src/main/java/com/hoc/flowmvi/App.kt
+++ b/app/src/main/java/com/hoc/flowmvi/App.kt
@@ -13,6 +13,7 @@ import org.koin.android.ext.koin.androidContext
 import org.koin.android.ext.koin.androidLogger
 import org.koin.core.context.startKoin
 import org.koin.core.logger.Level
+import timber.log.Timber
 import kotlin.time.ExperimentalTime
 
 @FlowPreview
@@ -37,6 +38,12 @@ class App : Application() {
   override fun onCreate() {
     super.onCreate()
 
+    if (BuildConfig.DEBUG) {
+      Timber.plant(Timber.DebugTree())
+    } else {
+      // TODO(Timber): plant release tree
+    }
+
     startKoin {
       androidContext(this@App)
 
diff --git a/buildSrc/src/main/kotlin/deps.kt b/buildSrc/src/main/kotlin/deps.kt
index a13252df..1cbfc9cf 100644
--- a/buildSrc/src/main/kotlin/deps.kt
+++ b/buildSrc/src/main/kotlin/deps.kt
@@ -69,6 +69,7 @@ object deps {
   const val coil = "io.coil-kt:coil:1.2.1"
   const val viewBindingDelegate = "com.github.hoc081098:ViewBindingDelegate:1.2.0"
   const val flowExt = "io.github.hoc081098:FlowExt:0.0.7-SNAPSHOT"
+  const val timber = "com.jakewharton.timber:timber:5.0.1"
 
   object arrow {
     private const val version = "1.0.1"
diff --git a/core/build.gradle.kts b/core/build.gradle.kts
index 25ef57b0..351e1704 100644
--- a/core/build.gradle.kts
+++ b/core/build.gradle.kts
@@ -49,5 +49,7 @@ dependencies {
   implementation(deps.lifecycle.commonJava8)
   implementation(deps.lifecycle.runtimeKtx)
 
+  implementation(deps.timber)
+
   addUnitTest()
 }
diff --git a/core/src/main/java/com/hoc/flowmvi/core/CollectIn.kt b/core/src/main/java/com/hoc/flowmvi/core/CollectIn.kt
index 13642a10..c80ff5fe 100644
--- a/core/src/main/java/com/hoc/flowmvi/core/CollectIn.kt
+++ b/core/src/main/java/com/hoc/flowmvi/core/CollectIn.kt
@@ -1,6 +1,5 @@
 package com.hoc.flowmvi.core
 
-import android.util.Log
 import androidx.fragment.app.Fragment
 import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.LifecycleOwner
@@ -10,6 +9,7 @@ import kotlinx.coroutines.Job
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.collect
 import kotlinx.coroutines.launch
+import timber.log.Timber
 
 inline fun <T> Flow<T>.collectIn(
   owner: LifecycleOwner,
@@ -17,7 +17,7 @@ inline fun <T> Flow<T>.collectIn(
   crossinline action: suspend (value: T) -> Unit,
 ): Job = owner.lifecycleScope.launch {
   owner.repeatOnLifecycle(state = minActiveState) {
-    Log.d("collectIn", "Start collecting $owner $minActiveState...")
+    Timber.d("Start collecting $owner $minActiveState...")
     collect { action(it) }
   }
 }
diff --git a/core/src/main/java/com/hoc/flowmvi/core/FlowBinding.kt b/core/src/main/java/com/hoc/flowmvi/core/FlowBinding.kt
index 4d2cccf5..29528fb0 100644
--- a/core/src/main/java/com/hoc/flowmvi/core/FlowBinding.kt
+++ b/core/src/main/java/com/hoc/flowmvi/core/FlowBinding.kt
@@ -2,7 +2,6 @@ package com.hoc.flowmvi.core
 
 import android.content.Context
 import android.os.Looper
-import android.util.Log
 import android.view.View
 import android.widget.EditText
 import android.widget.Toast
@@ -17,6 +16,7 @@ import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.callbackFlow
 import kotlinx.coroutines.flow.onStart
 import kotlinx.coroutines.flow.take
+import timber.log.Timber
 import kotlin.coroutines.EmptyCoroutineContext
 
 internal fun checkMainThread() {
@@ -35,7 +35,7 @@ fun EditText.firstChange(): Flow<Unit> {
     awaitClose {
       Dispatchers.Main.dispatch(EmptyCoroutineContext) {
         removeTextChangedListener(listener)
-        Log.d("###", "removeTextChangedListener $listener ${this@firstChange}")
+        Timber.d("removeTextChangedListener $listener $this")
       }
     }
   }.take(1)
diff --git a/data/build.gradle.kts b/data/build.gradle.kts
index 728d958d..412a1f59 100644
--- a/data/build.gradle.kts
+++ b/data/build.gradle.kts
@@ -52,5 +52,7 @@ dependencies {
   implementation(deps.koin.core)
   implementation(deps.arrow.core)
 
+  implementation(deps.timber)
+
   addUnitTest()
 }
diff --git a/data/src/main/java/com/hoc/flowmvi/data/UserRepositoryImpl.kt b/data/src/main/java/com/hoc/flowmvi/data/UserRepositoryImpl.kt
index d86a82c8..f2da9786 100644
--- a/data/src/main/java/com/hoc/flowmvi/data/UserRepositoryImpl.kt
+++ b/data/src/main/java/com/hoc/flowmvi/data/UserRepositoryImpl.kt
@@ -1,6 +1,5 @@
 package com.hoc.flowmvi.data
 
-import android.util.Log
 import arrow.core.Either
 import arrow.core.left
 import arrow.core.leftWiden
@@ -24,6 +23,7 @@ import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.flow.scan
 import kotlinx.coroutines.withContext
+import timber.log.Timber
 import java.io.IOException
 import kotlin.time.Duration
 import kotlin.time.ExperimentalTime
@@ -54,7 +54,7 @@ internal class UserRepositoryImpl(
         factor = 2.0,
         shouldRetry = { it is IOException }
       ) {
-        Log.d("###", "[USER_REPO] Retry times=$it")
+        Timber.d("[USER_REPO] Retry times=$it")
         userApiService.getUsers().map(responseToDomain)
       }
     }
@@ -64,7 +64,7 @@ internal class UserRepositoryImpl(
     val initial = getUsersFromRemote()
 
     changesFlow
-      .onEach { Log.d("###", "[USER_REPO] Change=$it") }
+      .onEach { Timber.d("[USER_REPO] Change=$it") }
       .scan(initial) { acc, change ->
         when (change) {
           is Change.Removed -> acc.filter { it.id != change.removed.id }
@@ -72,38 +72,45 @@ internal class UserRepositoryImpl(
           is Change.Added -> acc + change.user
         }
       }
-      .onEach { Log.d("###", "[USER_REPO] Emit users.size=${it.size} ") }
+      .onEach { Timber.d("[USER_REPO] Emit users.size=${it.size} ") }
       .let { emitAll(it) }
   }
     .map { it.right().leftWiden<UserError, Nothing, List<User>>() }
-    .catch { emit(errorMapper(it).left()) }
+    .catch {
+      Timber.tag("UserRepositoryImpl").e(it, "getUsers")
+      emit(errorMapper(it).left())
+    }
 
-  override suspend fun refresh() = Either.catch(errorMapper) {
+  override suspend fun refresh() = Either.catch {
     getUsersFromRemote().let { changesFlow.emit(Change.Refreshed(it)) }
-  }
+  }.tapLeft { Timber.tag("UserRepositoryImpl").e(it, "refresh") }
+    .mapLeft(errorMapper)
 
-  override suspend fun remove(user: User) = Either.catch(errorMapper) {
+  override suspend fun remove(user: User) = Either.catch {
     withContext(dispatchers.io) {
       val response = userApiService.remove(user.id)
       changesFlow.emit(Change.Removed(responseToDomain(response)))
     }
-  }
+  }.tapLeft { Timber.tag("UserRepositoryImpl").e(it, "remove user=$user") }
+    .mapLeft(errorMapper)
 
-  override suspend fun add(user: User) = Either.catch(errorMapper) {
+  override suspend fun add(user: User) = Either.catch {
     withContext(dispatchers.io) {
       val body = domainToBody(user)
       val response = userApiService.add(body)
       changesFlow.emit(Change.Added(responseToDomain(response)))
       extraDelay()
     }
-  }
+  }.tapLeft { Timber.tag("UserRepositoryImpl").e(it, "add user=$user") }
+    .mapLeft(errorMapper)
 
-  override suspend fun search(query: String) = Either.catch(errorMapper) {
+  override suspend fun search(query: String) = Either.catch {
     withContext(dispatchers.io) {
       extraDelay()
       userApiService.search(query).map(responseToDomain)
     }
-  }
+  }.tapLeft { Timber.tag("UserRepositoryImpl").e(it, "search query=$query") }
+    .mapLeft(errorMapper)
 
   private suspend inline fun extraDelay() = delay(400)
 }
diff --git a/feature-add/build.gradle.kts b/feature-add/build.gradle.kts
index 6a194817..b55d001e 100644
--- a/feature-add/build.gradle.kts
+++ b/feature-add/build.gradle.kts
@@ -58,6 +58,7 @@ dependencies {
 
   implementation(deps.viewBindingDelegate)
   implementation(deps.flowExt)
+  implementation(deps.timber)
 
   addUnitTest()
 }
diff --git a/feature-add/src/main/java/com/hoc/flowmvi/ui/add/AddActivity.kt b/feature-add/src/main/java/com/hoc/flowmvi/ui/add/AddActivity.kt
index 7ca729a5..91e97ab5 100644
--- a/feature-add/src/main/java/com/hoc/flowmvi/ui/add/AddActivity.kt
+++ b/feature-add/src/main/java/com/hoc/flowmvi/ui/add/AddActivity.kt
@@ -2,7 +2,6 @@ package com.hoc.flowmvi.ui.add
 
 import android.content.Context
 import android.content.Intent
-import android.util.Log
 import android.view.MenuItem
 import androidx.core.view.isInvisible
 import androidx.transition.AutoTransition
@@ -20,6 +19,7 @@ import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.merge
 import org.koin.androidx.viewmodel.ext.android.viewModel
+import timber.log.Timber
 
 @ExperimentalCoroutinesApi
 class AddActivity :
@@ -35,7 +35,7 @@ class AddActivity :
   }
 
   override fun handleSingleEvent(event: SingleEvent) {
-    Log.d("###", "Event=$event")
+    Timber.d("Event=$event")
 
     return when (event) {
       is SingleEvent.AddUserSuccess -> {
@@ -43,14 +43,13 @@ class AddActivity :
         finish()
       }
       is SingleEvent.AddUserFailure -> {
-        Log.d("###", event.toString())
         toast("Add failure")
       }
     }
   }
 
   override fun render(viewState: ViewState) {
-    Log.d("###", "ViewState=$viewState")
+    Timber.d("viewState=$viewState")
 
     val emailErrorMessage = if (ValidationError.INVALID_EMAIL_ADDRESS in viewState.errors) {
       "Invalid email"
diff --git a/feature-add/src/main/java/com/hoc/flowmvi/ui/add/AddVM.kt b/feature-add/src/main/java/com/hoc/flowmvi/ui/add/AddVM.kt
index 67d5616d..f0d5de90 100644
--- a/feature-add/src/main/java/com/hoc/flowmvi/ui/add/AddVM.kt
+++ b/feature-add/src/main/java/com/hoc/flowmvi/ui/add/AddVM.kt
@@ -1,6 +1,5 @@
 package com.hoc.flowmvi.ui.add
 
-import android.util.Log
 import androidx.core.util.PatternsCompat
 import androidx.lifecycle.SavedStateHandle
 import androidx.lifecycle.viewModelScope
@@ -31,6 +30,7 @@ import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.flow.onStart
 import kotlinx.coroutines.flow.scan
 import kotlinx.coroutines.flow.stateIn
+import timber.log.Timber
 
 @ExperimentalCoroutinesApi
 class AddVM(
@@ -46,13 +46,13 @@ class AddVM(
       firstName = savedStateHandle.get<String?>(FIRST_NAME_KEY),
       lastName = savedStateHandle.get<String?>(LAST_NAME_KEY),
     )
-    Log.d(logTag, "[ADD_VM] initialVS: $initialVS")
+    Timber.tag(logTag).d("[ADD_VM] initialVS: $initialVS")
 
     viewState = intentFlow
       .toPartialStateChangesFlow()
       .sendSingleEvent()
       .scan(initialVS) { state, change -> change.reduce(state) }
-      .catch { Log.d(logTag, "[ADD_VM] Throwable: $it") }
+      .catch { Timber.tag(logTag).e(it, "[ADD_VM] Throwable: $it") }
       .stateIn(viewModelScope, SharingStarted.Eagerly, initialVS)
   }
 
diff --git a/feature-main/build.gradle.kts b/feature-main/build.gradle.kts
index 3bce8ff3..2532aed4 100644
--- a/feature-main/build.gradle.kts
+++ b/feature-main/build.gradle.kts
@@ -67,6 +67,7 @@ dependencies {
   implementation(deps.viewBindingDelegate)
   implementation(deps.flowExt)
   implementation(deps.arrow.core)
+  implementation(deps.timber)
 
   addUnitTest()
   testImplementation(mviTesting)
diff --git a/feature-main/src/main/java/com/hoc/flowmvi/ui/main/MainActivity.kt b/feature-main/src/main/java/com/hoc/flowmvi/ui/main/MainActivity.kt
index 2b75a8a8..6f1cd622 100644
--- a/feature-main/src/main/java/com/hoc/flowmvi/ui/main/MainActivity.kt
+++ b/feature-main/src/main/java/com/hoc/flowmvi/ui/main/MainActivity.kt
@@ -1,6 +1,5 @@
 package com.hoc.flowmvi.ui.main
 
-import android.util.Log
 import android.view.Menu
 import android.view.MenuItem
 import androidx.core.view.isVisible
@@ -27,6 +26,7 @@ import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.merge
 import org.koin.android.ext.android.inject
 import org.koin.androidx.viewmodel.ext.android.viewModel
+import timber.log.Timber
 
 @FlowPreview
 @ExperimentalCoroutinesApi
@@ -81,7 +81,7 @@ class MainActivity :
   )
 
   override fun handleSingleEvent(event: SingleEvent) {
-    Log.d("MainActivity", "handleSingleEvent $event")
+    Timber.d("handleSingleEvent $event")
     return when (event) {
       SingleEvent.Refresh.Success -> toast("Refresh success")
       is SingleEvent.Refresh.Failure -> toast("Refresh failure")
@@ -92,7 +92,7 @@ class MainActivity :
   }
 
   override fun render(viewState: ViewState) {
-    Log.d("MainActivity", "render $viewState")
+    Timber.d("render $viewState")
 
     userAdapter.submitList(viewState.userItems)
 
diff --git a/feature-main/src/main/java/com/hoc/flowmvi/ui/main/MainVM.kt b/feature-main/src/main/java/com/hoc/flowmvi/ui/main/MainVM.kt
index e119906c..d5c07caf 100644
--- a/feature-main/src/main/java/com/hoc/flowmvi/ui/main/MainVM.kt
+++ b/feature-main/src/main/java/com/hoc/flowmvi/ui/main/MainVM.kt
@@ -1,6 +1,5 @@
 package com.hoc.flowmvi.ui.main
 
-import android.util.Log
 import androidx.lifecycle.viewModelScope
 import com.hoc.flowmvi.domain.usecase.GetUsersUseCase
 import com.hoc.flowmvi.domain.usecase.RefreshGetUsersUseCase
@@ -28,6 +27,7 @@ import kotlinx.coroutines.flow.onStart
 import kotlinx.coroutines.flow.scan
 import kotlinx.coroutines.flow.stateIn
 import kotlinx.coroutines.flow.take
+import timber.log.Timber
 
 @FlowPreview
 @ExperimentalCoroutinesApi
@@ -49,7 +49,7 @@ class MainVM(
       .toPartialChangeFlow()
       .sendSingleEvent()
       .scan(initialVS) { vs, change -> change.reduce(vs) }
-      .catch { Log.d("###", "[MAIN_VM] Throwable: $it") }
+      .catch { Timber.tag(logTag).e(it, "[MAIN_VM] Throwable: $it") }
       .stateIn(
         viewModelScope,
         SharingStarted.Eagerly,
@@ -79,7 +79,7 @@ class MainVM(
   private fun Flow<ViewIntent>.toPartialChangeFlow(): Flow<PartialChange> =
     shareWhileSubscribed().run {
       val getUserChanges = defer(getUsersUseCase::invoke)
-        .onEach { either -> Log.d("###", "[MAIN_VM] Emit users.size=${either.map { it.size }}") }
+        .onEach { either -> Timber.d("[MAIN_VM] Emit users.size=${either.map { it.size }}") }
         .map { result ->
           result.fold(
             ifLeft = { PartialChange.GetUser.Error(it) },
diff --git a/feature-search/build.gradle.kts b/feature-search/build.gradle.kts
index ddcc0ea9..0b0b5c7e 100644
--- a/feature-search/build.gradle.kts
+++ b/feature-search/build.gradle.kts
@@ -61,6 +61,7 @@ dependencies {
   implementation(deps.viewBindingDelegate)
   implementation(deps.flowExt)
   implementation(deps.arrow.core)
+  implementation(deps.timber)
 
   addUnitTest()
 }
diff --git a/feature-search/src/main/java/com/hoc/flowmvi/ui/search/SearchActivity.kt b/feature-search/src/main/java/com/hoc/flowmvi/ui/search/SearchActivity.kt
index 8b35599b..e0908242 100644
--- a/feature-search/src/main/java/com/hoc/flowmvi/ui/search/SearchActivity.kt
+++ b/feature-search/src/main/java/com/hoc/flowmvi/ui/search/SearchActivity.kt
@@ -3,7 +3,6 @@ package com.hoc.flowmvi.ui.search
 import android.content.Context
 import android.content.Intent
 import android.content.res.Configuration
-import android.util.Log
 import android.view.Menu
 import android.view.MenuItem
 import androidx.appcompat.widget.SearchView
@@ -30,6 +29,7 @@ import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.merge
 import kotlinx.coroutines.flow.onEach
 import org.koin.androidx.viewmodel.ext.android.viewModel
+import timber.log.Timber
 import kotlin.time.ExperimentalTime
 
 @ExperimentalCoroutinesApi
@@ -79,7 +79,7 @@ class SearchActivity :
   override fun viewIntents(): Flow<ViewIntent> = merge(
     searchViewQueryTextEventChannel
       .consumeAsFlow()
-      .onEach { Log.d("SearchActivity", "Query $it") }
+      .onEach { Timber.d("Query $it") }
       .map { ViewIntent.Search(it.query.toString()) },
     binding.retryButton.clicks().map { ViewIntent.Retry },
   )
diff --git a/feature-search/src/main/java/com/hoc/flowmvi/ui/search/SearchVM.kt b/feature-search/src/main/java/com/hoc/flowmvi/ui/search/SearchVM.kt
index 278f7955..ed66e68a 100644
--- a/feature-search/src/main/java/com/hoc/flowmvi/ui/search/SearchVM.kt
+++ b/feature-search/src/main/java/com/hoc/flowmvi/ui/search/SearchVM.kt
@@ -1,6 +1,5 @@
 package com.hoc.flowmvi.ui.search
 
-import android.util.Log
 import androidx.lifecycle.SavedStateHandle
 import androidx.lifecycle.viewModelScope
 import com.hoc.flowmvi.domain.usecase.SearchUsersUseCase
@@ -27,6 +26,7 @@ import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.flow.onStart
 import kotlinx.coroutines.flow.scan
 import kotlinx.coroutines.flow.stateIn
+import timber.log.Timber
 import kotlin.time.Duration
 import kotlin.time.ExperimentalTime
 
@@ -49,7 +49,7 @@ class SearchVM(
       .toPartialStateChangesFlow()
       .sendSingleEvent()
       .scan(initialVS) { state, change -> change.reduce(state) }
-      .catch { Log.d(logTag, "[SEARCH_VM] Throwable: $it") }
+      .catch { Timber.tag(logTag).e(it, "[SEARCH_VM] Throwable: $it") }
       .stateIn(viewModelScope, SharingStarted.Eagerly, initialVS)
   }
 
diff --git a/mvi/mvi-base/build.gradle.kts b/mvi/mvi-base/build.gradle.kts
index fe6f9c55..8773f946 100644
--- a/mvi/mvi-base/build.gradle.kts
+++ b/mvi/mvi-base/build.gradle.kts
@@ -38,6 +38,7 @@ dependencies {
   implementation(deps.coroutines.core)
 
   implementation(core)
+  implementation(deps.timber)
 
   addUnitTest()
 }
diff --git a/mvi/mvi-base/src/main/java/com/hoc/flowmvi/mvi_base/AbstractMviViewModel.kt b/mvi/mvi-base/src/main/java/com/hoc/flowmvi/mvi_base/AbstractMviViewModel.kt
index c47af2bd..caef665b 100644
--- a/mvi/mvi-base/src/main/java/com/hoc/flowmvi/mvi_base/AbstractMviViewModel.kt
+++ b/mvi/mvi-base/src/main/java/com/hoc/flowmvi/mvi_base/AbstractMviViewModel.kt
@@ -1,6 +1,6 @@
 package com.hoc.flowmvi.mvi_base
 
-import android.util.Log
+import android.os.Build
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import kotlinx.coroutines.channels.Channel
@@ -13,11 +13,19 @@ import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.flow.receiveAsFlow
 import kotlinx.coroutines.flow.shareIn
 import kotlinx.coroutines.flow.stateIn
+import timber.log.Timber
 
 abstract class AbstractMviViewModel<I : MviIntent, S : MviViewState, E : MviSingleEvent> :
   MviViewModel<I, S, E>, ViewModel() {
   protected val logTag by lazy(LazyThreadSafetyMode.PUBLICATION) {
-    this::class.java.simpleName.take(23)
+    this::class.java.simpleName.let { tag ->
+      // Tag length limit was removed in API 26.
+      if (tag.length <= MAX_TAG_LENGTH || Build.VERSION.SDK_INT >= 26) {
+        tag
+      } else {
+        tag.take(MAX_TAG_LENGTH)
+      }
+    }
   }
 
   private val eventChannel = Channel<E>(Channel.UNLIMITED)
@@ -34,7 +42,7 @@ abstract class AbstractMviViewModel<I : MviIntent, S : MviViewState, E : MviSing
   // Extensions on Flow using viewModelScope.
 
   protected fun <T> Flow<T>.log(subject: String): Flow<T> =
-    onEach { Log.d(logTag, ">>> $subject: $it") }
+    onEach { Timber.tag(logTag).d(">>> $subject: $it") }
 
   protected fun <T> Flow<T>.shareWhileSubscribed(): SharedFlow<T> =
     shareIn(viewModelScope, SharingStarted.WhileSubscribed())
@@ -52,5 +60,7 @@ abstract class AbstractMviViewModel<I : MviIntent, S : MviViewState, E : MviSing
      * We use replay=0 so buffer = 64.
      */
     private const val SubscriberBufferSize = 64
+
+    private const val MAX_TAG_LENGTH = 23
   }
 }
diff --git a/mvi/mvi-testing/build.gradle.kts b/mvi/mvi-testing/build.gradle.kts
index e8b54ff1..870df1a5 100644
--- a/mvi/mvi-testing/build.gradle.kts
+++ b/mvi/mvi-testing/build.gradle.kts
@@ -36,6 +36,7 @@ dependencies {
   implementation(deps.coroutines.core)
 
   implementation(mviBase)
+  implementation(deps.timber)
 
   addUnitTest(testImplementation = false)
 }