diff --git a/examples/repl/cmdline.rs b/examples/repl/cmdline.rs
index 838e5ffc0..df86235d1 100644
--- a/examples/repl/cmdline.rs
+++ b/examples/repl/cmdline.rs
@@ -269,7 +269,6 @@ async fn log_msglist(context: &Context, msglist: &[MsgId]) -> Result<()> {
 
 async fn log_contactlist(context: &Context, contacts: &[u32]) -> Result<()> {
     for contact_id in contacts {
-        let line;
         let mut line2 = "".to_string();
         let contact = Contact::get_by_id(context, *contact_id).await?;
         let name = contact.get_display_name();
@@ -284,21 +283,17 @@ async fn log_contactlist(context: &Context, contacts: &[u32]) -> Result<()> {
         } else {
             ""
         };
-        line = format!(
+        let line = format!(
             "{}{} <{}>",
             if !name.is_empty() {
-                &name
+                name
             } else {
                 "<name unset>"
             },
             verified_str,
-            if !addr.is_empty() {
-                &addr
-            } else {
-                "addr unset"
-            }
+            if !addr.is_empty() { addr } else { "addr unset" }
         );
-        let peerstate = Peerstate::from_addr(context, &addr)
+        let peerstate = Peerstate::from_addr(context, addr)
             .await
             .expect("peerstate error");
         if peerstate.is_some() && *contact_id != 1 {
@@ -771,7 +766,7 @@ pub async fn cmdline(context: Context, line: &str, chat_id: &mut ChatId) -> Resu
             chat::set_chat_name(
                 &context,
                 sel_chat.as_ref().unwrap().get_id(),
-                &format!("{} {}", arg1, arg2).trim(),
+                format!("{} {}", arg1, arg2).trim(),
             )
             .await?;
 
diff --git a/examples/repl/main.rs b/examples/repl/main.rs
index dc5aa6943..d2693a903 100644
--- a/examples/repl/main.rs
+++ b/examples/repl/main.rs
@@ -416,7 +416,7 @@ async fn handle_cmd(
         }
         "getqr" | "getbadqr" => {
             ctx.start_io().await;
-            let group = arg1.parse::<u32>().ok().map(|id| ChatId::new(id));
+            let group = arg1.parse::<u32>().ok().map(ChatId::new);
             let mut qr = dc_get_securejoin_qr(&ctx, group).await?;
             if !qr.is_empty() {
                 if arg0 == "getbadqr" && qr.len() > 40 {
@@ -433,7 +433,7 @@ async fn handle_cmd(
         }
         "getqrsvg" => {
             ctx.start_io().await;
-            let group = arg1.parse::<u32>().ok().map(|id| ChatId::new(id));
+            let group = arg1.parse::<u32>().ok().map(ChatId::new);
             let file = dirs::home_dir().unwrap_or_default().join("qr.svg");
             match get_securejoin_qr_svg(&ctx, group).await {
                 Ok(svg) => {
diff --git a/src/blob.rs b/src/blob.rs
index 3ba92b73a..1770af2a6 100644
--- a/src/blob.rs
+++ b/src/blob.rs
@@ -292,7 +292,7 @@ impl<'a> BlobObject<'a> {
 
     /// Returns the filename of the blob.
     pub fn as_file_name(&self) -> &str {
-        self.name.rsplitn(2, '/').next().unwrap()
+        self.name.rsplit('/').next().unwrap()
     }
 
     /// The path relative in the blob directory.
@@ -305,7 +305,7 @@ impl<'a> BlobObject<'a> {
     /// If a blob's filename has an extension, it is always guaranteed
     /// to be lowercase.
     pub fn suffix(&self) -> Option<&str> {
-        let ext = self.name.rsplitn(2, '.').next();
+        let ext = self.name.rsplit('.').next();
         if ext == Some(&self.name) {
             None
         } else {
diff --git a/src/chat.rs b/src/chat.rs
index a32f4c923..dd35e82ee 100644
--- a/src/chat.rs
+++ b/src/chat.rs
@@ -1160,7 +1160,7 @@ impl Chat {
     /// deltachat, and the data returned is still subject to change.
     pub async fn get_info(&self, context: &Context) -> Result<ChatInfo> {
         let draft = match self.id.get_draft(context).await? {
-            Some(message) => message.text.unwrap_or_else(String::new),
+            Some(message) => message.text.unwrap_or_default(),
             _ => String::new(),
         };
         Ok(ChatInfo {
diff --git a/src/contact.rs b/src/contact.rs
index aae6d8bc0..651283cca 100644
--- a/src/contact.rs
+++ b/src/contact.rs
@@ -1179,7 +1179,7 @@ async fn set_block_contact(context: &Context, contact_id: u32, new_blocking: boo
             .sql
             .execute(
                 "UPDATE contacts SET blocked=? WHERE id=?;",
-                paramsv![new_blocking as i32, contact_id as i32],
+                paramsv![i32::from(new_blocking), contact_id as i32],
             )
             .await?;
 
diff --git a/src/dc_receive_imf.rs b/src/dc_receive_imf.rs
index 79bb4c407..b7482b0e2 100644
--- a/src/dc_receive_imf.rs
+++ b/src/dc_receive_imf.rs
@@ -1372,7 +1372,7 @@ async fn is_probably_private_reply(
     // should be assigned to the group chat. We restrict this exception to classical emails, as chat-group-messages
     // contain a Chat-Group-Id header and can be sorted into the correct chat this way.
 
-    let private_message = to_ids == [DC_CONTACT_ID_SELF].iter().copied().collect::<Vec<u32>>();
+    let private_message = to_ids == [DC_CONTACT_ID_SELF];
     if !private_message {
         return Ok(false);
     }
@@ -1406,7 +1406,7 @@ async fn create_or_lookup_group(
     let grpid = if let Some(grpid) = try_getting_grpid(mime_parser) {
         grpid
     } else if allow_creation {
-        let mut member_ids: Vec<u32> = to_ids.iter().copied().collect();
+        let mut member_ids: Vec<u32> = to_ids.to_vec();
         if !member_ids.contains(&(from_id as u32)) {
             member_ids.push(from_id as u32);
         }
diff --git a/src/dc_tools.rs b/src/dc_tools.rs
index 46da3189e..0b61a4523 100644
--- a/src/dc_tools.rs
+++ b/src/dc_tools.rs
@@ -534,8 +534,8 @@ impl rusqlite::types::ToSql for EmailAddress {
 /// Makes sure that a user input that is not supposed to contain newlines does not contain newlines.
 pub(crate) fn improve_single_line_input(input: &str) -> String {
     input
-        .replace("\n", " ")
-        .replace("\r", " ")
+        .replace('\n', " ")
+        .replace('\r', " ")
         .trim()
         .to_string()
 }
diff --git a/src/html.rs b/src/html.rs
index 4ec781201..a7d0e5191 100644
--- a/src/html.rs
+++ b/src/html.rs
@@ -365,7 +365,7 @@ test some special html-characters as &lt; &gt; and &amp; but also &quot; and &#x
         // however, rust multiline-strings use just `\n`;
         // therefore, we just remove `\r` before comparison.
         assert_eq!(
-            parser.html.replace("\r", ""),
+            parser.html.replace('\r', ""),
             r##"
 <html>
   <p>mime-modified <b>set</b>; simplify is always regarded as lossy.</p>
@@ -379,7 +379,7 @@ test some special html-characters as &lt; &gt; and &amp; but also &quot; and &#x
         let raw = include_bytes!("../test-data/message/text_alt_html.eml");
         let parser = HtmlMsgParser::from_bytes(&t.ctx, raw).await.unwrap();
         assert_eq!(
-            parser.html.replace("\r", ""), // see comment in test_htmlparse_html()
+            parser.html.replace('\r', ""), // see comment in test_htmlparse_html()
             r##"<html>
   <p>mime-modified <b>set</b>; simplify is always regarded as lossy.</p>
 </html>
@@ -394,7 +394,7 @@ test some special html-characters as &lt; &gt; and &amp; but also &quot; and &#x
         let raw = include_bytes!("../test-data/message/text_alt_plain_html.eml");
         let parser = HtmlMsgParser::from_bytes(&t.ctx, raw).await.unwrap();
         assert_eq!(
-            parser.html.replace("\r", ""), // see comment in test_htmlparse_html()
+            parser.html.replace('\r', ""), // see comment in test_htmlparse_html()
             r##"<html>
   <p>
     this is <b>html</b>
diff --git a/src/imex.rs b/src/imex.rs
index 9423c84a9..95920b769 100644
--- a/src/imex.rs
+++ b/src/imex.rs
@@ -165,7 +165,6 @@ pub async fn initiate_key_transfer(context: &Context) -> Result<String> {
 }
 
 async fn do_initiate_key_transfer(context: &Context) -> Result<String> {
-    let mut msg: Message;
     let setup_code = create_setup_code(context);
     /* this may require a keypair to be created. this may take a second ... */
     let setup_file_content = render_setup_file(context, &setup_code).await?;
@@ -178,8 +177,10 @@ async fn do_initiate_key_transfer(context: &Context) -> Result<String> {
     .await?;
 
     let chat_id = ChatId::create_for_contact(context, DC_CONTACT_ID_SELF).await?;
-    msg = Message::default();
-    msg.viewtype = Viewtype::File;
+    let mut msg = Message {
+        viewtype: Viewtype::File,
+        ..Default::default()
+    };
     msg.param.set(Param::File, setup_file_blob.as_name());
     msg.subject = stock_str::ac_setup_msg_subject(context).await;
     msg.param
@@ -236,7 +237,7 @@ pub async fn render_setup_file(context: &Context, passphrase: &str) -> Result<St
 
     let msg_subj = stock_str::ac_setup_msg_subject(context).await;
     let msg_body = stock_str::ac_setup_msg_body(context).await;
-    let msg_body_html = msg_body.replace("\r", "").replace("\n", "<br>");
+    let msg_body_html = msg_body.replace('\r', "").replace('\n', "<br>");
     Ok(format!(
         concat!(
             "<!DOCTYPE html>\r\n",
diff --git a/src/key.rs b/src/key.rs
index 5d1276b63..688030fc3 100644
--- a/src/key.rs
+++ b/src/key.rs
@@ -297,8 +297,8 @@ pub async fn store_self_keypair(
             .context("failed to clear default")?;
     }
     let is_default = match default {
-        KeyPairUse::Default => true as i32,
-        KeyPairUse::ReadOnly => false as i32,
+        KeyPairUse::Default => i32::from(true),
+        KeyPairUse::ReadOnly => i32::from(false),
     };
 
     let addr = keypair.addr.to_string();
diff --git a/src/location.rs b/src/location.rs
index bebd0c5ea..6f1505a78 100644
--- a/src/location.rs
+++ b/src/location.rs
@@ -101,10 +101,10 @@ impl Kml {
             let val = event.unescape_and_decode(reader).unwrap_or_default();
 
             let val = val
-                .replace("\n", "")
-                .replace("\r", "")
-                .replace("\t", "")
-                .replace(" ", "");
+                .replace('\n', "")
+                .replace('\r', "")
+                .replace('\t', "")
+                .replace(' ', "");
 
             if self.tag.contains(KmlTag::WHEN) && val.len() >= 19 {
                 // YYYY-MM-DDTHH:MM:SSZ
diff --git a/src/peerstate.rs b/src/peerstate.rs
index 7df1460ac..2dbc9a228 100644
--- a/src/peerstate.rs
+++ b/src/peerstate.rs
@@ -379,10 +379,9 @@ impl Peerstate {
     pub fn peek_key(&self, min_verified: PeerstateVerifiedStatus) -> Option<&SignedPublicKey> {
         match min_verified {
             PeerstateVerifiedStatus::BidirectVerified => self.verified_key.as_ref(),
-            PeerstateVerifiedStatus::Unverified => self
-                .public_key
-                .as_ref()
-                .or_else(|| self.gossip_key.as_ref()),
+            PeerstateVerifiedStatus::Unverified => {
+                self.public_key.as_ref().or(self.gossip_key.as_ref())
+            }
         }
     }
 
diff --git a/src/plaintext.rs b/src/plaintext.rs
index 9b49a5483..0f1082ea5 100644
--- a/src/plaintext.rs
+++ b/src/plaintext.rs
@@ -41,7 +41,7 @@ impl PlainText {
             // as <http://example.org> cannot be handled correctly
             // (they would become &lt;http://example.org&gt; where the trailing &gt; would become a valid url part).
             // to avoid double encoding, we escape our html-entities by \r that must not be used in the string elsewhere.
-            let line = line.to_string().replace("\r", "");
+            let line = line.to_string().replace('\r', "");
 
             let mut line = LINKIFY_MAIL_RE
                 .replace_all(&*line, "\rLTa href=\rQUOTmailto:$1\rQUOT\rGT$1\rLT/a\rGT")
diff --git a/src/provider.rs b/src/provider.rs
index 13dafd1bd..bdba76a65 100644
--- a/src/provider.rs
+++ b/src/provider.rs
@@ -113,7 +113,7 @@ pub async fn get_provider_info(
     domain: &str,
     skip_mx: bool,
 ) -> Option<&'static Provider> {
-    let domain = domain.rsplitn(2, '@').next()?;
+    let domain = domain.rsplit('@').next()?;
 
     if let Some(provider) = get_provider_by_domain(domain) {
         return Some(provider);
diff --git a/src/qr.rs b/src/qr.rs
index 9e91a2ecd..a0e669b26 100644
--- a/src/qr.rs
+++ b/src/qr.rs
@@ -173,7 +173,7 @@ async fn decode_openpgp(context: &Context, qr: &str) -> Result<Qr> {
     };
 
     let name = if let Some(encoded_name) = param.get("n") {
-        let encoded_name = encoded_name.replace("+", "%20"); // sometimes spaces are encoded as `+`
+        let encoded_name = encoded_name.replace('+', "%20"); // sometimes spaces are encoded as `+`
         match percent_decode_str(&encoded_name).decode_utf8() {
             Ok(name) => name.to_string(),
             Err(err) => bail!("Invalid name: {}", err),
@@ -188,7 +188,7 @@ async fn decode_openpgp(context: &Context, qr: &str) -> Result<Qr> {
 
     let grpname = if grpid.is_some() {
         if let Some(encoded_name) = param.get("g") {
-            let encoded_name = encoded_name.replace("+", "%20"); // sometimes spaces are encoded as `+`
+            let encoded_name = encoded_name.replace('+', "%20"); // sometimes spaces are encoded as `+`
             match percent_decode_str(&encoded_name).decode_utf8() {
                 Ok(name) => Some(name.to_string()),
                 Err(err) => bail!("Invalid group name: {}", err),
diff --git a/src/simplify.rs b/src/simplify.rs
index 06f6bc37d..74d2dcfde 100644
--- a/src/simplify.rs
+++ b/src/simplify.rs
@@ -240,7 +240,7 @@ fn render_message(lines: &[&str], is_cut_at_end: bool) -> String {
         ret += " [...]";
     }
     // redo escaping done by escape_message_footer_marks()
-    ret.replace("\u{200B}", "")
+    ret.replace('\u{200B}', "")
 }
 
 /// Returns true if the line contains only whitespace.
diff --git a/src/smtp.rs b/src/smtp.rs
index 7537c7400..45a03106d 100644
--- a/src/smtp.rs
+++ b/src/smtp.rs
@@ -246,7 +246,7 @@ pub(crate) async fn smtp_send(
                             // Other enhanced status codes, such as Postfix
                             // "550 5.1.1 <foobar@example.org>: Recipient address rejected: User unknown in local recipient table"
                             // are not ignored.
-                            response.first_word() == Some(&"5.5.0".to_string())
+                            response.first_word() == Some("5.5.0")
                         }
                         _ => false,
                     };