diff --git a/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/CustomTabsLauncher.kt b/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/CustomTabsLauncher.kt
index ce5af44b..ea0137f3 100644
--- a/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/CustomTabsLauncher.kt
+++ b/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/CustomTabsLauncher.kt
@@ -20,7 +20,6 @@ import com.github.droibit.flutter.plugins.customtabs.core.ExternalBrowserLaunche
 import com.github.droibit.flutter.plugins.customtabs.core.NativeAppLauncher
 import com.github.droibit.flutter.plugins.customtabs.core.PartialCustomTabsLauncher
 import com.github.droibit.flutter.plugins.customtabs.core.session.CustomTabsSessionManager
-import com.github.droibit.flutter.plugins.customtabs.core.utils.CODE_LAUNCH_ERROR
 
 @RestrictTo(RestrictTo.Scope.LIBRARY)
 internal class CustomTabsLauncher @VisibleForTesting constructor(
@@ -153,4 +152,8 @@ internal class CustomTabsLauncher @VisibleForTesting constructor(
             pm.resolveService(intent, flags)
         }
     }
+
+    private companion object {
+        const val CODE_LAUNCH_ERROR = "LAUNCH_ERROR"
+    }
 }
diff --git a/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/core/CustomTabsIntentFactory.kt b/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/core/CustomTabsIntentFactory.kt
index d2ad39f1..32335fbe 100644
--- a/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/core/CustomTabsIntentFactory.kt
+++ b/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/core/CustomTabsIntentFactory.kt
@@ -16,7 +16,7 @@ import com.github.droibit.flutter.plugins.customtabs.core.options.CustomTabsColo
 import com.github.droibit.flutter.plugins.customtabs.core.options.CustomTabsIntentOptions
 import com.github.droibit.flutter.plugins.customtabs.core.options.PartialCustomTabsConfiguration
 import com.github.droibit.flutter.plugins.customtabs.core.session.CustomTabsSessionProvider
-import com.github.droibit.flutter.plugins.customtabs.core.utils.extractBundle
+import com.github.droibit.flutter.plugins.customtabs.core.utils.bundleOf
 
 class CustomTabsIntentFactory @VisibleForTesting internal constructor(
     private val resources: ResourceFactory
@@ -130,7 +130,7 @@ class CustomTabsIntentFactory @VisibleForTesting internal constructor(
         options: BrowserConfiguration
     ) {
         val rawIntent = customTabsIntent.intent
-        options.headers?.let { rawIntent.putExtra(EXTRA_HEADERS, extractBundle(it)) }
+        options.headers?.let { rawIntent.putExtra(EXTRA_HEADERS, bundleOf(it)) }
 
         // Avoid overriding the package if using CustomTabsSession.
         if (rawIntent.getPackage() != null) {
diff --git a/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/core/ExternalBrowserLauncher.kt b/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/core/ExternalBrowserLauncher.kt
index cdb22c3f..e887c05b 100644
--- a/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/core/ExternalBrowserLauncher.kt
+++ b/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/core/ExternalBrowserLauncher.kt
@@ -6,7 +6,7 @@ import android.net.Uri
 import android.provider.Browser.EXTRA_HEADERS
 import androidx.annotation.VisibleForTesting
 import com.github.droibit.flutter.plugins.customtabs.core.options.CustomTabsIntentOptions
-import com.github.droibit.flutter.plugins.customtabs.core.utils.extractBundle
+import com.github.droibit.flutter.plugins.customtabs.core.utils.bundleOf
 
 class ExternalBrowserLauncher {
     fun launch(context: Context, uri: Uri, options: CustomTabsIntentOptions?): Boolean {
@@ -26,7 +26,7 @@ class ExternalBrowserLauncher {
         val browserOptions = options.browser ?: return null
         val prefersExternalBrowser = browserOptions.prefersExternalBrowser
         if (prefersExternalBrowser == true) {
-            browserOptions.headers?.let { intent.putExtra(EXTRA_HEADERS, extractBundle(it)) }
+            browserOptions.headers?.let { intent.putExtra(EXTRA_HEADERS, bundleOf(it)) }
             return intent
         }
         return null
diff --git a/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/core/PartialCustomTabsLauncher.kt b/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/core/PartialCustomTabsLauncher.kt
index db422fc1..34fa655c 100644
--- a/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/core/PartialCustomTabsLauncher.kt
+++ b/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/core/PartialCustomTabsLauncher.kt
@@ -5,7 +5,6 @@ import android.net.Uri
 import androidx.browser.customtabs.CustomTabsIntent
 import androidx.browser.customtabs.CustomTabsIntent.EXTRA_ACTIVITY_HEIGHT_RESIZE_BEHAVIOR
 import androidx.browser.customtabs.CustomTabsIntent.EXTRA_INITIAL_ACTIVITY_HEIGHT_PX
-import com.github.droibit.flutter.plugins.customtabs.core.utils.REQUEST_CODE_PARTIAL_CUSTOM_TABS
 
 class PartialCustomTabsLauncher {
     fun launch(activity: Activity, uri: Uri, customTabsIntent: CustomTabsIntent): Boolean {
@@ -20,4 +19,8 @@ class PartialCustomTabsLauncher {
         }
         return false
     }
+
+    private companion object {
+        const val REQUEST_CODE_PARTIAL_CUSTOM_TABS = 1001
+    }
 }
diff --git a/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/core/utils/Utils.kt b/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/core/utils/Utils.kt
index 60bb19f2..2f1f9635 100644
--- a/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/core/utils/Utils.kt
+++ b/flutter_custom_tabs_android/android/src/main/kotlin/com/github/droibit/flutter/plugins/customtabs/core/utils/Utils.kt
@@ -4,10 +4,7 @@ import android.os.Bundle
 
 internal const val TAG = "CustomTabsAndroid"
 
-internal const val CODE_LAUNCH_ERROR: String = "LAUNCH_ERROR"
-internal const val REQUEST_CODE_PARTIAL_CUSTOM_TABS = 1001
-
-internal fun extractBundle(headers: Map<String, String>): Bundle {
+internal fun bundleOf(headers: Map<String, String>): Bundle {
     return Bundle(headers.size).apply {
         for ((key, value) in headers) {
             putString(key, value)