diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index a5bcd30b..4c496bef 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -59,7 +59,7 @@ jobs:
             - name: Test
               run: |
                 set -euo pipefail
-                go test -count=1 -covermode=atomic -coverpkg ./... -p 1 -v -json $(go list ./... | grep -v tests-e2e) -coverprofile synccoverage.out 2>&1 | tee ./test-integration.log | gotestfmt -hide all
+                go test -count=1 -race -covermode=atomic -coverpkg ./... -p 1 -v -json $(go list ./... | grep -v tests-e2e) -coverprofile synccoverage.out 2>&1 | tee ./test-integration.log | gotestfmt -hide all
               shell: bash
               env:
                   POSTGRES_HOST: localhost
diff --git a/pubsub/pubsub.go b/pubsub/pubsub.go
index dea3efe1..f3132ae8 100644
--- a/pubsub/pubsub.go
+++ b/pubsub/pubsub.go
@@ -84,7 +84,11 @@ func (ps *PubSub) Notify(chanName string, p Payload) error {
 		return fmt.Errorf("notify with payload %v timed out", p.Type())
 	}
 	if ps.bufferSize == 0 {
+		// for some reason go test -race flags this as racing with calls
+		// to close(ch), despite the fact that it _should_ be thread-safe :S
+		ps.mu.Lock()
 		ch <- &emptyPayload{}
+		ps.mu.Unlock()
 	}
 	return nil
 }
diff --git a/state/accumulator_test.go b/state/accumulator_test.go
index db358830..5d95b0b4 100644
--- a/state/accumulator_test.go
+++ b/state/accumulator_test.go
@@ -4,12 +4,14 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"github.com/matrix-org/sliding-sync/testutils"
 	"reflect"
 	"sort"
 	"sync"
+	"sync/atomic"
 	"testing"
 
+	"github.com/matrix-org/sliding-sync/testutils"
+
 	"github.com/jmoiron/sqlx"
 	"github.com/matrix-org/sliding-sync/sqlutil"
 	"github.com/matrix-org/sliding-sync/sync2"
@@ -680,7 +682,7 @@ func TestAccumulatorConcurrency(t *testing.T) {
 		[]byte(`{"event_id":"con_4", "type":"m.room.name", "state_key":"", "content":{"name":"4"}}`),
 		[]byte(`{"event_id":"con_5", "type":"m.room.name", "state_key":"", "content":{"name":"5"}}`),
 	}
-	totalNumNew := 0
+	var totalNumNew atomic.Int64
 	var wg sync.WaitGroup
 	wg.Add(len(newEvents))
 	for i := 0; i < len(newEvents); i++ {
@@ -689,7 +691,7 @@ func TestAccumulatorConcurrency(t *testing.T) {
 			subset := newEvents[:(i + 1)] // i=0 => [1], i=1 => [1,2], etc
 			err := sqlutil.WithTransaction(accumulator.db, func(txn *sqlx.Tx) error {
 				result, err := accumulator.Accumulate(txn, userID, roomID, sync2.TimelineResponse{Events: subset})
-				totalNumNew += result.NumNew
+				totalNumNew.Add(int64(result.NumNew))
 				return err
 			})
 			if err != nil {
@@ -698,8 +700,8 @@ func TestAccumulatorConcurrency(t *testing.T) {
 		}(i)
 	}
 	wg.Wait() // wait for all goroutines to finish
-	if totalNumNew != len(newEvents) {
-		t.Errorf("got %d total new events, want %d", totalNumNew, len(newEvents))
+	if int(totalNumNew.Load()) != len(newEvents) {
+		t.Errorf("got %d total new events, want %d", totalNumNew.Load(), len(newEvents))
 	}
 	// check that the name of the room is "5"
 	snapshot := currentSnapshotNIDs(t, accumulator.snapshotTable, roomID)
diff --git a/sync2/poller_test.go b/sync2/poller_test.go
index 1ce7a745..4b145aab 100644
--- a/sync2/poller_test.go
+++ b/sync2/poller_test.go
@@ -25,12 +25,23 @@ const initialSinceToken = "0"
 var (
 	timeSinceMu    sync.Mutex
 	timeSinceValue = time.Duration(0) // 0 means use the real impl
+	timeSleepMu    sync.Mutex
+	timeSleepValue = time.Duration(0)  // 0 means use the real impl
+	timeSleepCheck func(time.Duration) // called to check sleep values
 )
 
 func setTimeSinceValue(val time.Duration) {
 	timeSinceMu.Lock()
+	defer timeSinceMu.Unlock()
 	timeSinceValue = val
-	timeSinceMu.Unlock()
+}
+func setTimeSleepDelay(val time.Duration, fn ...func(d time.Duration)) {
+	timeSleepMu.Lock()
+	defer timeSleepMu.Unlock()
+	timeSleepValue = val
+	if len(fn) > 0 {
+		timeSleepCheck = fn[0]
+	}
 }
 func init() {
 	timeSince = func(t time.Time) time.Duration {
@@ -41,6 +52,18 @@ func init() {
 		}
 		return timeSinceValue
 	}
+	timeSleep = func(d time.Duration) {
+		timeSleepMu.Lock()
+		defer timeSleepMu.Unlock()
+		if timeSleepCheck != nil {
+			timeSleepCheck(d)
+		}
+		if timeSleepValue == 0 {
+			time.Sleep(d)
+			return
+		}
+		time.Sleep(timeSleepValue)
+	}
 }
 
 // Tests that EnsurePolling works in the happy case
@@ -583,12 +606,10 @@ func TestPollerGivesUpEventually(t *testing.T) {
 	accumulator, client := newMocks(func(authHeader, since string) (*SyncResponse, int, error) {
 		return nil, 524, fmt.Errorf("gateway timeout")
 	})
-	timeSleep = func(d time.Duration) {
-		// actually sleep to make sure async actions can happen if any
-		time.Sleep(1 * time.Microsecond)
-	}
+	// actually sleep to make sure async actions can happen if any
+	setTimeSleepDelay(time.Microsecond)
 	defer func() { // reset the value after the test runs
-		timeSleep = time.Sleep
+		setTimeSleepDelay(0)
 	}()
 	var wg sync.WaitGroup
 	wg.Add(1)
@@ -654,15 +675,13 @@ func TestPollerBackoff(t *testing.T) {
 		wantBackoffDuration = errorResponses[i].backoff
 		return nil, errorResponses[i].code, errorResponses[i].err
 	})
-	timeSleep = func(d time.Duration) {
+	setTimeSleepDelay(time.Millisecond, func(d time.Duration) {
 		if d != wantBackoffDuration {
 			t.Errorf("time.Sleep called incorrectly: got %v want %v", d, wantBackoffDuration)
 		}
-		// actually sleep to make sure async actions can happen if any
-		time.Sleep(1 * time.Millisecond)
-	}
+	})
 	defer func() { // reset the value after the test runs
-		timeSleep = time.Sleep
+		setTimeSleepDelay(0)
 	}()
 	var wg sync.WaitGroup
 	wg.Add(1)
@@ -727,12 +746,10 @@ func TestPollerResendsOnCallbackError(t *testing.T) {
 	pid := PollerID{UserID: "@TestPollerResendsOnCallbackError:localhost", DeviceID: "FOOBAR"}
 
 	defer func() { // reset the value after the test runs
-		timeSleep = time.Sleep
+		setTimeSleepDelay(0)
 	}()
 	// we don't actually want to wait 3s between retries, so monkey patch it out
-	timeSleep = func(d time.Duration) {
-		time.Sleep(time.Millisecond)
-	}
+	setTimeSleepDelay(time.Millisecond)
 
 	testCases := []struct {
 		name             string
diff --git a/sync3/connmap_test.go b/sync3/connmap_test.go
index 8fbcf8cd..adf3aaf4 100644
--- a/sync3/connmap_test.go
+++ b/sync3/connmap_test.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"reflect"
 	"sort"
+	"sync/atomic"
 	"testing"
 	"time"
 
@@ -201,15 +202,15 @@ func assertDestroyedConns(t *testing.T, cidToConn map[ConnID]*Conn, isDestroyedF
 	t.Helper()
 	for cid, conn := range cidToConn {
 		if isDestroyedFn(cid) {
-			mustEqual(t, conn.handler.(*mockConnHandler).isDestroyed, true, fmt.Sprintf("conn %+v was not destroyed", cid))
+			mustEqual(t, conn.handler.(*mockConnHandler).isDestroyed.Load(), true, fmt.Sprintf("conn %+v was not destroyed", cid))
 		} else {
-			mustEqual(t, conn.handler.(*mockConnHandler).isDestroyed, false, fmt.Sprintf("conn %+v was destroyed", cid))
+			mustEqual(t, conn.handler.(*mockConnHandler).isDestroyed.Load(), false, fmt.Sprintf("conn %+v was destroyed", cid))
 		}
 	}
 }
 
 type mockConnHandler struct {
-	isDestroyed bool
+	isDestroyed atomic.Bool
 	cancel      context.CancelFunc
 }
 
@@ -219,7 +220,7 @@ func (c *mockConnHandler) OnIncomingRequest(ctx context.Context, cid ConnID, req
 func (c *mockConnHandler) OnUpdate(ctx context.Context, update caches.Update) {}
 func (c *mockConnHandler) PublishEventsUpTo(roomID string, nid int64)         {}
 func (c *mockConnHandler) Destroy() {
-	c.isDestroyed = true
+	c.isDestroyed.Store(true)
 }
 func (c *mockConnHandler) Alive() bool {
 	return true // buffer never fills up
diff --git a/tests-integration/poller_test.go b/tests-integration/poller_test.go
index 5ce3b4dd..3c3fae06 100644
--- a/tests-integration/poller_test.go
+++ b/tests-integration/poller_test.go
@@ -4,14 +4,15 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"github.com/jmoiron/sqlx"
-	"github.com/matrix-org/sliding-sync/sqlutil"
 	"net/http"
 	"os"
 	"sync/atomic"
 	"testing"
 	"time"
 
+	"github.com/jmoiron/sqlx"
+	"github.com/matrix-org/sliding-sync/sqlutil"
+
 	"github.com/matrix-org/sliding-sync/sync2"
 	"github.com/matrix-org/sliding-sync/sync3"
 	"github.com/matrix-org/sliding-sync/sync3/extensions"
@@ -45,7 +46,7 @@ func TestSecondPollerFiltersToDevice(t *testing.T) {
 	// now sync with device B, and check we send the filter up
 	deviceBToken := "DEVICE_B_TOKEN"
 	v2.addAccountWithDeviceID(alice, "B", deviceBToken)
-	seenInitialRequest := false
+	var seenInitialRequest atomic.Bool
 	v2.SetCheckRequest(func(token string, req *http.Request) {
 		if token != deviceBToken {
 			return
@@ -62,7 +63,7 @@ func TestSecondPollerFiltersToDevice(t *testing.T) {
 		timelineLimit := filterJSON.Get("room.timeline.limit").Int()
 		roomsFilter := filterJSON.Get("room.rooms")
 
-		if !seenInitialRequest {
+		if !seenInitialRequest.Load() {
 			// First poll: should be an initial sync, limit 1, excluding all room timelines.
 			if since != "" {
 				t.Errorf("Expected no since token on first poll, but got %v", since)
@@ -89,7 +90,7 @@ func TestSecondPollerFiltersToDevice(t *testing.T) {
 			}
 		}
 
-		seenInitialRequest = true
+		seenInitialRequest.Store(true)
 	})
 
 	wantMsg := json.RawMessage(`{"type":"f","content":{"f":"b"}}`)
@@ -110,7 +111,7 @@ func TestSecondPollerFiltersToDevice(t *testing.T) {
 		},
 	})
 
-	if !seenInitialRequest {
+	if !seenInitialRequest.Load() {
 		t.Fatalf("did not see initial request for 2nd device")
 	}
 	// the first request will not wait for the response before returning due to device A. Poll again