diff --git a/mailpot-cli/src/commands.rs b/mailpot-cli/src/commands.rs
index d3f8be5..d6647c8 100644
--- a/mailpot-cli/src/commands.rs
+++ b/mailpot-cli/src/commands.rs
@@ -434,11 +434,7 @@ pub fn list(db: &mut Connection, list_id: &str, cmd: ListCommand, quiet: bool) -
                 for e in entries {
                     println!(
                         "{}{}<{}>",
-                        if let Some(n) = e.display_name() {
-                            n
-                        } else {
-                            ""
-                        },
+                        e.display_name().unwrap_or_default(),
                         if e.display_name().is_none() { "" } else { " " },
                         e.email()
                     );
@@ -449,11 +445,7 @@ pub fn list(db: &mut Connection, list_id: &str, cmd: ListCommand, quiet: bool) -
                     for e in entries {
                         println!(
                             "{}{}<{}>",
-                            if let Some(n) = e.display_name() {
-                                n
-                            } else {
-                                ""
-                            },
+                            e.display_name().unwrap_or_default(),
                             if e.display_name().is_none() { "" } else { " " },
                             e.email()
                         );
diff --git a/mailpot/src/connection.rs b/mailpot/src/connection.rs
index 5f122eb..3d675ed 100644
--- a/mailpot/src/connection.rs
+++ b/mailpot/src/connection.rs
@@ -362,6 +362,7 @@ impl Connection {
                 stdin
                     .write_all(Self::SCHEMA.as_bytes())
                     .expect("failed to write to stdin");
+                #[allow(clippy::const_is_empty)]
                 if !Self::MIGRATIONS.is_empty() {
                     stdin
                         .write_all(b"\nPRAGMA user_version = ")
@@ -962,11 +963,11 @@ pub mod transaction {
 
     impl Transaction<'_> {
         /// Commit and consume transaction.
-        pub fn commit(mut self) -> Result<()> {
+        pub fn commit(self) -> Result<()> {
             self.commit_()
         }
 
-        fn commit_(&mut self) -> Result<()> {
+        fn commit_(&self) -> Result<()> {
             self.conn.connection.execute_batch("COMMIT")?;
             Ok(())
         }
@@ -980,11 +981,11 @@ pub mod transaction {
 
         /// A convenience method which consumes and rolls back a transaction.
         #[inline]
-        pub fn rollback(mut self) -> Result<()> {
+        pub fn rollback(self) -> Result<()> {
             self.rollback_()
         }
 
-        fn rollback_(&mut self) -> Result<()> {
+        fn rollback_(&self) -> Result<()> {
             self.conn.connection.execute_batch("ROLLBACK")?;
             Ok(())
         }
@@ -995,12 +996,12 @@ pub mod transaction {
         /// Functionally equivalent to the `Drop` implementation, but allows
         /// callers to see any errors that occur.
         #[inline]
-        pub fn finish(mut self) -> Result<()> {
+        pub fn finish(self) -> Result<()> {
             self.finish_()
         }
 
         #[inline]
-        fn finish_(&mut self) -> Result<()> {
+        fn finish_(&self) -> Result<()> {
             if self.conn.connection.is_autocommit() {
                 return Ok(());
             }
@@ -1106,11 +1107,11 @@ pub mod transaction {
 
         /// A convenience method which consumes and rolls back a savepoint.
         #[inline]
-        pub fn rollback(mut self) -> Result<()> {
+        pub fn rollback(self) -> Result<()> {
             self.rollback_()
         }
 
-        fn rollback_(&mut self) -> Result<()> {
+        fn rollback_(&self) -> Result<()> {
             if !self.committed {
                 match self.name {
                     Ok(ref n) => self
diff --git a/mailpot/tests/migrations.rs b/mailpot/tests/migrations.rs
index 69d8da6..faeb476 100644
--- a/mailpot/tests/migrations.rs
+++ b/mailpot/tests/migrations.rs
@@ -168,7 +168,7 @@ fn test_migration_gen() {
             .write(true)
             .create(true)
             .truncate(true)
-            .open(&in_path.join(&format!("{num:03}.sql")))
+            .open(in_path.join(&format!("{num:03}.sql")))
             .unwrap();
         redo_file.write_all(redo.as_bytes()).unwrap();
         redo_file.flush().unwrap();
@@ -177,7 +177,7 @@ fn test_migration_gen() {
             .write(true)
             .create(true)
             .truncate(true)
-            .open(&in_path.join(&format!("{num:03}.undo.sql")))
+            .open(in_path.join(&format!("{num:03}.undo.sql")))
             .unwrap();
         undo_file.write_all(undo.as_bytes()).unwrap();
         undo_file.flush().unwrap();
@@ -202,7 +202,7 @@ fn test_migration_gen_panic() {
             .write(true)
             .create(true)
             .truncate(true)
-            .open(&in_path.join(&format!("{num:03}.sql")))
+            .open(in_path.join(&format!("{num:03}.sql")))
             .unwrap();
         redo_file.write_all(redo.as_bytes()).unwrap();
         redo_file.flush().unwrap();
@@ -211,7 +211,7 @@ fn test_migration_gen_panic() {
             .write(true)
             .create(true)
             .truncate(true)
-            .open(&in_path.join(&format!("{num:03}.undo.sql")))
+            .open(in_path.join(&format!("{num:03}.undo.sql")))
             .unwrap();
         undo_file.write_all(undo.as_bytes()).unwrap();
         undo_file.flush().unwrap();