diff --git a/API/TelegramAPIDefinition.yml b/API/TelegramAPIDefinition.yml
index 449d4e7..ad32694 100644
--- a/API/TelegramAPIDefinition.yml
+++ b/API/TelegramAPIDefinition.yml
@@ -254,7 +254,7 @@ fields:
     - type: PollType
     - allows_multiple_answers: Bool
     - correct_option_id: Int?
-    - explanation: String
+    - explanation: String?
     - explanation_entities: MessageEntity[]?
     - open_period: Int?
     - close_date: Date?
diff --git a/Sources/TelegramBotSDK/Generated/Types.swift b/Sources/TelegramBotSDK/Generated/Types.swift
index e90debc..bf29bdc 100644
--- a/Sources/TelegramBotSDK/Generated/Types.swift
+++ b/Sources/TelegramBotSDK/Generated/Types.swift
@@ -467,11 +467,11 @@ public class Poll: Codable {
     public var type: PollType
     public var allowsMultipleAnswers: Bool
     public var correctOptionId: Int?
-    public var explanation: String
+    public var explanation: String?
     public var explanationEntities: [MessageEntity]? = []
     public var openPeriod: Int?
     public var closeDate: Date?
-    public init(id: String, question: String, options: [PollOption], totalVoterCount: Int, isClosed: Bool, isAnonymous: Bool, type: PollType, allowsMultipleAnswers: Bool, correctOptionId: Int? = nil, explanation: String, explanationEntities: [MessageEntity]? = nil, openPeriod: Int? = nil, closeDate: Date? = nil) {
+    public init(id: String, question: String, options: [PollOption], totalVoterCount: Int, isClosed: Bool, isAnonymous: Bool, type: PollType, allowsMultipleAnswers: Bool, correctOptionId: Int? = nil, explanation: String? = nil, explanationEntities: [MessageEntity]? = nil, openPeriod: Int? = nil, closeDate: Date? = nil) {
         self.id = id
         self.question = question
         self.options = options