diff --git a/lettre/src/file/error.rs b/lettre/src/file/error.rs
index 8a5ada3..b02bfd3 100644
--- a/lettre/src/file/error.rs
+++ b/lettre/src/file/error.rs
@@ -34,7 +34,7 @@ impl StdError for Error {
         }
     }
 
-    fn cause(&self) -> Option<&StdError> {
+    fn cause(&self) -> Option<&dyn StdError> {
         match *self {
             Io(ref err) => Some(&*err),
             JsonSerialization(ref err) => Some(&*err),
diff --git a/lettre/src/lib.rs b/lettre/src/lib.rs
index 245569b..698d8ca 100644
--- a/lettre/src/lib.rs
+++ b/lettre/src/lib.rs
@@ -126,7 +126,7 @@ impl Envelope {
 }
 
 pub enum Message {
-    Reader(Box<Read + Send>),
+    Reader(Box<dyn Read + Send>),
     Bytes(Cursor<Vec<u8>>),
 }
 
@@ -158,7 +158,7 @@ impl SendableEmail {
     pub fn new_with_reader(
         envelope: Envelope,
         message_id: String,
-        message: Box<Read + Send>,
+        message: Box<dyn Read + Send>,
     ) -> SendableEmail {
         SendableEmail {
             envelope,
diff --git a/lettre/src/sendmail/error.rs b/lettre/src/sendmail/error.rs
index 0198240..5ffd738 100644
--- a/lettre/src/sendmail/error.rs
+++ b/lettre/src/sendmail/error.rs
@@ -34,7 +34,7 @@ impl StdError for Error {
         }
     }
 
-    fn cause(&self) -> Option<&StdError> {
+    fn cause(&self) -> Option<&dyn StdError> {
         match *self {
             Io(ref err) => Some(&*err),
             Utf8Parsing(ref err) => Some(&*err),
diff --git a/lettre/src/smtp/client/mod.rs b/lettre/src/smtp/client/mod.rs
index fa413d8..5fd5901 100644
--- a/lettre/src/smtp/client/mod.rs
+++ b/lettre/src/smtp/client/mod.rs
@@ -194,7 +194,7 @@ impl<S: Connector + Write + Read + Timeout + Debug> InnerClient<S> {
     }
 
     /// Sends the message content
-    pub fn message(&mut self, message: Box<Read>) -> SmtpResult {
+    pub fn message(&mut self, message: Box<dyn Read>) -> SmtpResult {
         let mut out_buf: Vec<u8> = vec![];
         let mut codec = ClientCodec::new();
 
diff --git a/lettre/src/smtp/error.rs b/lettre/src/smtp/error.rs
index 100f049..c459177 100644
--- a/lettre/src/smtp/error.rs
+++ b/lettre/src/smtp/error.rs
@@ -71,7 +71,7 @@ impl StdError for Error {
         }
     }
 
-    fn cause(&self) -> Option<&StdError> {
+    fn cause(&self) -> Option<&dyn StdError> {
         match *self {
             ChallengeParsing(ref err) => Some(&*err),
             Utf8Parsing(ref err) => Some(&*err),