diff --git a/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/permission/AbstractConcurrentPermissionService.kt b/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/permission/AbstractConcurrentPermissionService.kt
index 933b24a9d..5bfd5f14d 100644
--- a/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/permission/AbstractConcurrentPermissionService.kt
+++ b/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/permission/AbstractConcurrentPermissionService.kt
@@ -12,6 +12,9 @@ package net.mamoe.mirai.console.permission
 import net.mamoe.mirai.console.permission.PermissibleIdentifier.Companion.grantedWith
 import java.util.concurrent.CopyOnWriteArrayList
 
+/**
+ *
+ */
 @ExperimentalPermission
 public abstract class AbstractConcurrentPermissionService<P : Permission> : PermissionService<P> {
     protected abstract val permissions: MutableMap<PermissionId, P>
@@ -28,9 +31,8 @@ public abstract class AbstractConcurrentPermissionService<P : Permission> : Perm
     override fun register(id: PermissionId, description: String, base: PermissionId): P {
         grantedPermissionsMap[id] = CopyOnWriteArrayList() // mutations are not quite often performed
         val instance = createPermission(id, description, base)
-        if (permissions.putIfAbsent(id, instance) != null) {
-            throw DuplicatedPermissionRegistrationException("Duplicated Permission registry. new: $instance, old: ${permissions[id]}")
-        }
+        val old = permissions.putIfAbsent(id, instance)
+        if (old != null) throw DuplicatedPermissionRegistrationException(instance, old)
         return instance
     }
 
diff --git a/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/permission/BuiltInPermissionServices.kt b/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/permission/BuiltInPermissionServices.kt
index 7cd656046..d873ffcc9 100644
--- a/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/permission/BuiltInPermissionServices.kt
+++ b/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/permission/BuiltInPermissionServices.kt
@@ -35,9 +35,8 @@ public object AllGrantPermissionService : PermissionService<PermissionImpl> {
         base: PermissionId
     ): PermissionImpl {
         val new = PermissionImpl(id, description, base)
-        if (all.putIfAbsent(id, new) != null) {
-            throw DuplicatedPermissionRegistrationException("Duplicated Permission registry: ${all[id]}")
-        }
+        val old = all.putIfAbsent(id, new)
+        if (old != null) throw DuplicatedPermissionRegistrationException(new, old)
         return new
     }
 
@@ -67,9 +66,8 @@ public object AllDenyPermissionService : PermissionService<PermissionImpl> {
         base: PermissionId
     ): PermissionImpl {
         val new = PermissionImpl(id, description, base)
-        if (all.putIfAbsent(id, new) != null) {
-            throw DuplicatedPermissionRegistrationException("Duplicated Permission registry: ${all[id]}")
-        }
+        val old = all.putIfAbsent(id, new)
+        if (old != null) throw DuplicatedPermissionRegistrationException(new, old)
         return new
     }
 
diff --git a/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/permission/DuplicatedPermissionRegistrationException.kt b/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/permission/DuplicatedPermissionRegistrationException.kt
index b521e1703..39cbb2807 100644
--- a/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/permission/DuplicatedPermissionRegistrationException.kt
+++ b/backend/mirai-console/src/main/kotlin/net/mamoe/mirai/console/permission/DuplicatedPermissionRegistrationException.kt
@@ -7,14 +7,12 @@
  * https://github.com/mamoe/mirai/blob/master/LICENSE
  */
 
-@file:Suppress("unused")
+@file:Suppress("unused", "MemberVisibilityCanBePrivate", "CanBeParameter")
 
 package net.mamoe.mirai.console.permission
 
 @ExperimentalPermission
-public open class DuplicatedPermissionRegistrationException : Exception {
-    public constructor() : super()
-    public constructor(message: String?) : super(message)
-    public constructor(message: String?, cause: Throwable?) : super(message, cause)
-    public constructor(cause: Throwable?) : super(cause)
-}
\ No newline at end of file
+public class DuplicatedPermissionRegistrationException(
+    newInstance: Permission,
+    public val existingInstance: Permission
+) : Exception("Duplicated Permission registry. new: $newInstance, existing: $existingInstance")
\ No newline at end of file