diff --git a/crates/common/src/manager/defaults.rs b/crates/common/src/manager/defaults.rs
index 1dd6ceaa..26211b2d 100644
--- a/crates/common/src/manager/defaults.rs
+++ b/crates/common/src/manager/defaults.rs
@@ -613,6 +613,8 @@ async fn insert_safe_defaults(bp: &mut Bootstrap) -> trc::Result<()> {
 /// of never; spam training samples are kept 90 days instead of 180; Pyzor,
 /// which sends a digest of each message's text to a public server, is off;
 /// delivery history is kept 14 days instead of 30.
+// Test builds leave out the caller (`cfg(not(feature = "test_mode"))`).
+#[cfg_attr(feature = "test_mode", allow(dead_code))]
 fn new_install_privacy_defaults(
     security: &mut Security,
     classifier: &mut SpamClassifier,
diff --git a/crates/http/src/live.rs b/crates/http/src/live.rs
index 02b6f8b3..7cf067ca 100644
--- a/crates/http/src/live.rs
+++ b/crates/http/src/live.rs
@@ -39,7 +39,7 @@ struct Slot;
 impl Slot {
     fn take() -> Option<Slot> {
         STREAMS
-            .fetch_update(Ordering::SeqCst, Ordering::SeqCst, |n| {
+            .try_update(Ordering::SeqCst, Ordering::SeqCst, |n| {
                 (n < MAX_STREAMS).then_some(n + 1)
             })
             .ok()
diff --git a/crates/services/src/task_manager/scheduler.rs b/crates/services/src/task_manager/scheduler.rs
index 72e6a884..16a025b0 100644
--- a/crates/services/src/task_manager/scheduler.rs
+++ b/crates/services/src/task_manager/scheduler.rs
@@ -48,7 +48,9 @@ enum Event {
     EvaluateAlerts,
     // inbuxa: settings-reorg: probe the other nodes' ports
     ProbePeerPorts,
-    // inbuxa: re-queue DKIM rotation and ACME renewal tasks a domain is missing
+    // inbuxa: re-queue DKIM rotation and ACME renewal tasks a domain is missing.
+    // Test builds never schedule it (`cfg(not(feature = "test_mode"))`).
+    #[cfg_attr(feature = "test_mode", allow(dead_code))]
     CheckDomainTasks,
 }
 
diff --git a/tests/src/system/front_ends.rs b/tests/src/system/front_ends.rs
index ef9e079e..b1f80716 100644
--- a/tests/src/system/front_ends.rs
+++ b/tests/src/system/front_ends.rs
@@ -153,7 +153,7 @@ fn refusal(response: &Value) -> String {
 #[ignore]
 #[tokio::test(flavor = "multi_thread")]
 pub async fn front_ends_tests() {
-    let mut test = TestServerBuilder::new("front_ends_tests")
+    let test = TestServerBuilder::new("front_ends_tests")
         .await
         .with_default_listeners()
         .await
diff --git a/tests/src/system/sharing_policy.rs b/tests/src/system/sharing_policy.rs
index c11c0b69..e12e9b51 100644
--- a/tests/src/system/sharing_policy.rs
+++ b/tests/src/system/sharing_policy.rs
@@ -95,7 +95,7 @@ impl Account {
 #[ignore]
 #[tokio::test(flavor = "multi_thread")]
 pub async fn sharing_policy_tests() {
-    let mut test = TestServerBuilder::new("sharing_policy_tests")
+    let test = TestServerBuilder::new("sharing_policy_tests")
         .await
         .with_default_listeners()
         .await