diff --git a/.config/nextest.toml b/.config/nextest.toml
index ba28fa0625..32fe543655 100644
--- a/.config/nextest.toml
+++ b/.config/nextest.toml
@@ -33,6 +33,11 @@ clickhouse-cluster = { max-threads = 1 }
 filter = 'package(oximeter-db) and test(replicated)'
 test-group = 'clickhouse-cluster'
 
+[[profile.default.overrides]]
+# These tests can time out under heavy contention.
+filter = 'binary_id(omicron-nexus::test_all) and test(::schema::)'
+threads-required = 4
+
 [[profile.ci.overrides]]
 filter = 'binary_id(omicron-nexus::test_all)'
 # As of 2023-01-08, the slowest test in test_all takes 196s on a Ryzen 7950X.
diff --git a/nexus/tests/integration_tests/schema.rs b/nexus/tests/integration_tests/schema.rs
index f183b53282..872627728e 100644
--- a/nexus/tests/integration_tests/schema.rs
+++ b/nexus/tests/integration_tests/schema.rs
@@ -479,10 +479,14 @@ async fn nexus_applies_update_on_boot() {
     // Start Nexus. It should auto-format itself to the latest version,
     // upgrading through each intermediate update.
     //
+    // The timeout here is a bit longer than usual (120s vs 60s) because if
+    // lots of tests are running at the same time, there can be contention
+    // here.
+    //
     // NOTE: If this grows excessively, we could break it into several smaller
     // tests.
     assert!(
-        timeout(Duration::from_secs(60), builder.start_nexus_internal())
+        timeout(Duration::from_secs(120), builder.start_nexus_internal())
             .await
             .is_ok(),
         "Nexus should have started"