diff --git a/go/logic/coordinator.go b/go/logic/coordinator.go
index 1921daffc..f3ee4942f 100644
--- a/go/logic/coordinator.go
+++ b/go/logic/coordinator.go
@@ -377,9 +377,11 @@ func (c *Coordinator) ProcessEventsUntilDrained() error {
 
 				switch binlogEvent := ev.Event.(type) {
 				case *replication.GTIDEvent:
+					c.mu.Lock()
 					if c.lowWaterMark == 0 && binlogEvent.SequenceNumber > 0 {
 						c.lowWaterMark = binlogEvent.SequenceNumber - 1
 					}
+					c.mu.Unlock()
 				case *replication.RotateEvent:
 					c.currentCoordinatesMutex.Lock()
 					c.currentCoordinates.LogFile = string(binlogEvent.NextLogName)
diff --git a/go/logic/migrator.go b/go/logic/migrator.go
index 39c248009..d90598ddc 100644
--- a/go/logic/migrator.go
+++ b/go/logic/migrator.go
@@ -1319,7 +1319,9 @@ func (this *Migrator) executeWriteFuncs() error {
 
 		// We give higher priority to event processing.
 		// ProcessEventsUntilDrained will process all events in the queue, and then return once no more events are available.
-		this.trxCoordinator.ProcessEventsUntilDrained()
+		if err := this.trxCoordinator.ProcessEventsUntilDrained(); err != nil {
+			return this.migrationContext.Log.Errore(err)
+		}
 
 		this.throttler.throttle(nil)
 
diff --git a/script/test b/script/test
index bec4f67f5..3f66288d1 100755
--- a/script/test
+++ b/script/test
@@ -14,4 +14,4 @@ script/build
 cd .gopath/src/github.com/github/gh-ost
 
 echo "Running unit tests"
-go test -v -p 1 -covermode=atomic ./go/...
+go test -v -p 1 -covermode=atomic -race ./go/...