diff --git a/tsdb/engine/tsm1/engine.go b/tsdb/engine/tsm1/engine.go
index cd161eb797..80e8f14e99 100644
--- a/tsdb/engine/tsm1/engine.go
+++ b/tsdb/engine/tsm1/engine.go
@@ -98,7 +98,9 @@ type Engine struct {
 	traceLogging bool
 
 	// TODO(benbjohnson): Index needs to be moved entirely into engine.
-	index             *tsdb.DatabaseIndex
+	index *tsdb.DatabaseIndex
+
+	fieldsMu          sync.RWMutex
 	measurementFields map[string]*tsdb.MeasurementFields
 
 	WAL            *WAL
@@ -286,21 +288,21 @@ func (e *Engine) Index() *tsdb.DatabaseIndex {
 
 // MeasurementFields returns the measurement fields for a measurement.
 func (e *Engine) MeasurementFields(measurement string) *tsdb.MeasurementFields {
-	e.mu.RLock()
+	e.fieldsMu.RLock()
 	m := e.measurementFields[measurement]
-	e.mu.RUnlock()
+	e.fieldsMu.RUnlock()
 
 	if m != nil {
 		return m
 	}
 
-	e.mu.Lock()
+	e.fieldsMu.Lock()
 	m = e.measurementFields[measurement]
 	if m == nil {
 		m = tsdb.NewMeasurementFields()
 		e.measurementFields[measurement] = m
 	}
-	e.mu.Unlock()
+	e.fieldsMu.Unlock()
 	return m
 }
 
@@ -628,11 +630,13 @@ func (e *Engine) addToIndexFromKey(shardID uint64, key []byte, fieldType influxq
 	m := index.CreateMeasurementIndexIfNotExists(measurement)
 	m.SetFieldName(field)
 
+	e.fieldsMu.Lock()
 	mf := e.measurementFields[measurement]
 	if mf == nil {
 		mf = tsdb.NewMeasurementFields()
 		e.measurementFields[measurement] = mf
 	}
+	e.fieldsMu.Unlock()
 
 	if err := mf.CreateFieldIfNotExists(field, fieldType, false); err != nil {
 		return err
@@ -803,9 +807,9 @@ func (e *Engine) DeleteSeriesRange(seriesKeys []string, min, max int64) error {
 
 // DeleteMeasurement deletes a measurement and all related series.
 func (e *Engine) DeleteMeasurement(name string, seriesKeys []string) error {
-	e.mu.Lock()
+	e.fieldsMu.Lock()
 	delete(e.measurementFields, name)
-	e.mu.Unlock()
+	e.fieldsMu.Unlock()
 
 	return e.DeleteSeries(seriesKeys)
 }
@@ -1537,9 +1541,9 @@ func (e *Engine) createVarRefSeriesIterator(ref *influxql.VarRef, mm *tsdb.Measu
 // buildCursor creates an untyped cursor for a field.
 func (e *Engine) buildCursor(measurement, seriesKey string, ref *influxql.VarRef, opt influxql.IteratorOptions) cursor {
 	// Look up fields for measurement.
-	e.mu.RLock()
+	e.fieldsMu.RLock()
 	mf := e.measurementFields[measurement]
-	e.mu.RUnlock()
+	e.fieldsMu.RUnlock()
 
 	if mf == nil {
 		return nil