diff --git a/mirai-core-utils/src/commonMain/kotlin/TypeSafeMap.kt b/mirai-core-utils/src/commonMain/kotlin/TypeSafeMap.kt
index c897ca65e..e14ce975b 100644
--- a/mirai-core-utils/src/commonMain/kotlin/TypeSafeMap.kt
+++ b/mirai-core-utils/src/commonMain/kotlin/TypeSafeMap.kt
@@ -1,10 +1,10 @@
 /*
- * Copyright 2019-2021 Mamoe Technologies and contributors.
+ * Copyright 2019-2022 Mamoe Technologies and contributors.
  *
- *  此源代码的使用受 GNU AFFERO GENERAL PUBLIC LICENSE version 3 许可证的约束, 可以在以下链接找到该许可证.
- *  Use of this source code is governed by the GNU AGPLv3 license that can be found through the following link.
+ * 此源代码的使用受 GNU AFFERO GENERAL PUBLIC LICENSE version 3 许可证的约束, 可以在以下链接找到该许可证.
+ * Use of this source code is governed by the GNU AGPLv3 license that can be found through the following link.
  *
- *  https://github.com/mamoe/mirai/blob/master/LICENSE
+ * https://github.com/mamoe/mirai/blob/dev/LICENSE
  */
 
 @file:Suppress("NOTHING_TO_INLINE")
@@ -31,7 +31,7 @@ public sealed interface TypeSafeMap {
     public val size: Int
 
     public operator fun <T> get(key: TypeKey<T>): T
-    public operator fun <T> get(key: TypeKey<T>, defaultValue: T): T
+    public operator fun <T : S, S> get(key: TypeKey<T>, defaultValue: S): S
     public operator fun <T> contains(key: TypeKey<T>): Boolean = get(key) != null
 
     public fun toMapBoxed(): Map<TypeKey<*>, Any?>
@@ -81,7 +81,7 @@ internal open class TypeSafeMapImpl(
     override operator fun <T> get(key: TypeKey<T>): T =
         map[key.name]?.uncheckedCast() ?: throw NoSuchElementException(key.toString())
 
-    override operator fun <T> get(key: TypeKey<T>, defaultValue: T): T =
+    override operator fun <T : S, S> get(key: TypeKey<T>, defaultValue: S): S =
         map[key.name]?.uncheckedCast() ?: defaultValue
 
     override operator fun <T> contains(key: TypeKey<T>): Boolean = map.containsKey(key.name)