diff --git a/build/ninja_gen/src/python.rs b/build/ninja_gen/src/python.rs
index d3e04845c..1e770741c 100644
--- a/build/ninja_gen/src/python.rs
+++ b/build/ninja_gen/src/python.rs
@@ -190,7 +190,7 @@ impl BuildAction for PythonFormat<'_> {
 pub fn python_format(build: &mut Build, group: &str, inputs: BuildInput) -> Result<()> {
     let isort_ini = &inputs![".isort.cfg"];
     build.add_action(
-        &format!("check:format:python:{group}"),
+        format!("check:format:python:{group}"),
         PythonFormat {
             inputs: &inputs,
             check_only: true,
@@ -199,7 +199,7 @@ pub fn python_format(build: &mut Build, group: &str, inputs: BuildInput) -> Resu
     )?;
 
     build.add_action(
-        &format!("format:python:{group}"),
+        format!("format:python:{group}"),
         PythonFormat {
             inputs: &inputs,
             check_only: false,
diff --git a/build/runner/src/bundle/binary.rs b/build/runner/src/bundle/binary.rs
index 995587c0c..e9119220a 100644
--- a/build/runner/src/bundle/binary.rs
+++ b/build/runner/src/bundle/binary.rs
@@ -46,7 +46,7 @@ pub fn build_bundle_binary() {
             .join("Toolchains/XcodeDefault.xctoolchain/usr/bin/ld-classic");
         if ld_classic.exists() {
             // work around XCode 15's default linker not supporting macOS 10.15-12.
-            command.env("RUSTFLAGS", &format!("-Clink-arg=-fuse-ld={ld_classic}"));
+            command.env("RUSTFLAGS", format!("-Clink-arg=-fuse-ld={ld_classic}"));
         }
     }
     run_command(&mut command);
diff --git a/rslib/i18n/src/lib.rs b/rslib/i18n/src/lib.rs
index 7c78cf71c..1d79198bf 100644
--- a/rslib/i18n/src/lib.rs
+++ b/rslib/i18n/src/lib.rs
@@ -464,7 +464,7 @@ pub struct ResourcesForJavascript {
 }
 
 pub fn without_unicode_isolation(s: &str) -> String {
-    s.replace(|c| c == '\u{2068}' || c == '\u{2069}', "")
+    s.replace(['\u{2068}', '\u{2069}'], "")
 }
 
 #[cfg(test)]
diff --git a/rslib/src/browser_table.rs b/rslib/src/browser_table.rs
index 830f1b54a..be4e6393e 100644
--- a/rslib/src/browser_table.rs
+++ b/rslib/src/browser_table.rs
@@ -131,8 +131,7 @@ impl Card {
         } else {
             self.due_time(timing).map(|due| {
                 due.adding_secs(-86_400 * self.interval as i64)
-                    .elapsed_secs()
-                    .max(0) as u32
+                    .elapsed_secs() as u32
                     / 86_400
             })
         }
diff --git a/rslib/src/dbcheck.rs b/rslib/src/dbcheck.rs
index fa66d2b9e..ae960ab5c 100644
--- a/rslib/src/dbcheck.rs
+++ b/rslib/src/dbcheck.rs
@@ -394,7 +394,7 @@ impl Collection {
         let qfmt = basic.templates[0].config.q_format.clone();
         let afmt = basic.templates[0].config.a_format.clone();
         for n in 0..extra_cards_required {
-            basic.add_template(&format!("Card {}", n + 2), &qfmt, &afmt);
+            basic.add_template(format!("Card {}", n + 2), &qfmt, &afmt);
         }
         self.add_notetype(&mut basic, true)?;
         Ok(Arc::new(basic))
diff --git a/rslib/src/sync/http_server/mod.rs b/rslib/src/sync/http_server/mod.rs
index 7759f3383..f96209df7 100644
--- a/rslib/src/sync/http_server/mod.rs
+++ b/rslib/src/sync/http_server/mod.rs
@@ -223,7 +223,7 @@ impl SimpleServer {
         let config = envy::prefixed("SYNC_")
             .from_env::<SyncServerConfig>()
             .unwrap();
-        std::net::TcpStream::connect(&format!("{}:{}", config.host, config.port)).is_ok()
+        std::net::TcpStream::connect(format!("{}:{}", config.host, config.port)).is_ok()
     }
     pub fn new(base_folder: &Path) -> error::Result<Self, Whatever> {
         let inner = SimpleServerInner::new_from_env(base_folder)?;
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
index 1ccbe9f82..3c1f3ff7a 100644
--- a/rust-toolchain.toml
+++ b/rust-toolchain.toml
@@ -1,3 +1,3 @@
 [toolchain]
 # older versions may fail to compile; newer versions may fail the clippy tests
-channel = "1.80.1"
+channel = "1.81.0"