diff --git a/crates/arti-client/src/client.rs b/crates/arti-client/src/client.rs
index aac3a3434..29a6e7bcf 100644
--- a/crates/arti-client/src/client.rs
+++ b/crates/arti-client/src/client.rs
@@ -313,6 +313,7 @@ impl<R: Runtime> TorClient<R> {
     /// Calling this function is usually preferable to creating a
     /// completely separate TorClient instance, since it can share its
     /// internals with the existing `TorClient`.
+    #[must_use]
     pub fn isolated_client(&self) -> TorClient<R> {
         let mut result = self.clone();
         result.client_isolation = IsolationToken::new();
diff --git a/crates/tor-checkable/src/timed.rs b/crates/tor-checkable/src/timed.rs
index 44024c450..ee8972460 100644
--- a/crates/tor-checkable/src/timed.rs
+++ b/crates/tor-checkable/src/timed.rs
@@ -67,12 +67,14 @@ impl<T> TimerangeBound<T> {
 
     /// Adjust this time-range bound to tolerate an expiration time farther
     /// in the future.
+    #[must_use]
     pub fn extend_tolerance(self, d: time::Duration) -> Self {
         let end = self.end.map(|t| t + d);
         Self { end, ..self }
     }
     /// Adjust this time-range bound to tolerate an initial validity
     /// time farther in the past.
+    #[must_use]
     pub fn extend_pre_tolerance(self, d: time::Duration) -> Self {
         let start = self.start.map(|t| t - d);
         Self { start, ..self }
diff --git a/crates/tor-config/src/err.rs b/crates/tor-config/src/err.rs
index 284406236..65025b2fd 100644
--- a/crates/tor-config/src/err.rs
+++ b/crates/tor-config/src/err.rs
@@ -40,6 +40,7 @@ impl From<derive_builder::UninitializedFieldError> for ConfigBuildError {
 impl ConfigBuildError {
     /// Return a new ConfigBuildError that prefixes its field name with
     /// `prefix` and a dot.
+    #[must_use]
     pub fn within(&self, prefix: &str) -> Self {
         use ConfigBuildError::*;
         match self {
diff --git a/crates/tor-netdoc/src/doc/netstatus.rs b/crates/tor-netdoc/src/doc/netstatus.rs
index b31092a81..b2c0f4a4c 100644
--- a/crates/tor-netdoc/src/doc/netstatus.rs
+++ b/crates/tor-netdoc/src/doc/netstatus.rs
@@ -1386,6 +1386,7 @@ impl<RS> UnvalidatedConsensus<RS> {
     /// Tell the unvalidated consensus how many authorities we believe in.
     ///
     /// Without knowing this number, we can't validate the signature.
+    #[must_use]
     pub fn set_n_authorities(self, n_authorities: u16) -> Self {
         UnvalidatedConsensus {
             n_authorities: Some(n_authorities),
diff --git a/crates/tor-netdoc/src/err.rs b/crates/tor-netdoc/src/err.rs
index 92ca34887..bd4fd99f3 100644
--- a/crates/tor-netdoc/src/err.rs
+++ b/crates/tor-netdoc/src/err.rs
@@ -116,6 +116,7 @@ impl Pos {
     ///
     /// TODO: I wish I knew an efficient safe way to do this that
     /// guaranteed that we we always talking about the right string.
+    #[must_use]
     pub fn within(self, s: &str) -> Self {
         match self {
             Pos::Byte { off } => Self::from_offset(s, off),
@@ -358,6 +359,7 @@ impl Error {
 
     /// Return a new error based on this one, with any byte-based
     /// position mapped to some line within a string.
+    #[must_use]
     pub fn within(mut self, s: &str) -> Error {
         if let Some(p) = self.pos_mut() {
             *p = p.within(s);
@@ -367,6 +369,7 @@ impl Error {
 
     /// Return a new error based on this one, with the position (if
     /// any) replaced by 'p'.
+    #[must_use]
     pub fn at_pos(mut self, p: Pos) -> Error {
         if let Some(mypos) = self.pos_mut() {
             *mypos = p;
@@ -376,6 +379,7 @@ impl Error {
 
     /// Return a new error based on this one, with the position (if
     /// replaced by 'p' if it had no position before.
+    #[must_use]
     pub fn or_at_pos(mut self, p: Pos) -> Error {
         if let Some(mypos) = self.pos_mut() {
             if *mypos == Pos::None {
diff --git a/crates/tor-persist/src/testing.rs b/crates/tor-persist/src/testing.rs
index e405f65da..d5bc11d3e 100644
--- a/crates/tor-persist/src/testing.rs
+++ b/crates/tor-persist/src/testing.rs
@@ -64,6 +64,7 @@ impl TestingStateMgr {
 
     /// Create a new unlocked [`TestingStateMgr`] that shares the same
     /// underlying storage with this one.
+    #[must_use]
     pub fn new_manager(&self) -> Self {
         let inner = self.inner.lock().expect("Lock poisoned.");
         let new_inner = TestingStateMgrInner {