diff --git a/TelegramBotAPI/src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/utils/extensions/String.kt b/TelegramBotAPI/src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/utils/extensions/String.kt
index f40c30df2b..3d8215326f 100644
--- a/TelegramBotAPI/src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/utils/extensions/String.kt
+++ b/TelegramBotAPI/src/commonMain/kotlin/com/github/insanusmokrassar/TelegramBotAPI/utils/extensions/String.kt
@@ -16,8 +16,8 @@ fun String.toMarkdown(): String {
     )
 }
 
-private val markdownV2LinkEscapes = mutableSetOf(')', '\\')
-private val markdownV2PreAndCodeEscapes = mutableSetOf('`', '\\')
+private val markdownV2LinkEscapes = setOf(')', '\\')
+private val markdownV2PreAndCodeEscapes = setOf('`', '\\')
 private val markdownV2CommonEscapes = setOf(
     '_',
     '*',