diff --git a/CHANGELOG.md b/CHANGELOG.md
index 887e19ae..e63789b8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -52,12 +52,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Make `SendPoll::poll_` optional ([#133][pr133])
 - Bug with `caption_entities`, see issue [#473][issue473]
 - Type of response for `CopyMessage` method ([#141](pr141), [#142](pr142))
+- Bad request serialization when the `language` field of `MessageEntityKind::Pre` is `None` ([#145](pr145))
 
 [pr119]: https://github.com/teloxide/teloxide-core/pull/119
 [pr133]: https://github.com/teloxide/teloxide-core/pull/133
 [pr141]: https://github.com/teloxide/teloxide-core/pull/141
 [pr142]: https://github.com/teloxide/teloxide-core/pull/142
 [pr143]: https://github.com/teloxide/teloxide-core/pull/143
+[pr145]: https://github.com/teloxide/teloxide-core/pull/145
 [issue473]: https://github.com/teloxide/teloxide/issues/473
 [issue427]: https://github.com/teloxide/teloxide/issues/427
 
diff --git a/src/types/message_entity.rs b/src/types/message_entity.rs
index 1f4873c8..cd8b6278 100644
--- a/src/types/message_entity.rs
+++ b/src/types/message_entity.rs
@@ -44,6 +44,7 @@ impl MessageEntity {
     }
 }
 
+#[serde_with_macros::skip_serializing_none]
 #[derive(Clone, Debug, Eq, Hash, PartialEq, Serialize, Deserialize)]
 #[serde(rename_all = "snake_case")]
 #[serde(tag = "type")]
@@ -104,4 +105,21 @@ mod tests {
                 .unwrap()
         );
     }
+
+    // https://github.com/teloxide/teloxide-core/pull/145
+    #[test]
+    fn pre_with_none_language() {
+        use serde_json::to_string;
+
+        assert_eq!(
+            to_string(&MessageEntity {
+                kind: MessageEntityKind::Pre { language: None },
+                offset: 1,
+                length: 2,
+            })
+            .unwrap()
+            .find("language"),
+            None
+        );
+    }
 }