diff --git a/mgr.go b/mgr.go
index 016b113..9d47980 100644
--- a/mgr.go
+++ b/mgr.go
@@ -191,8 +191,9 @@ func (m *mgr) Query(q QuerySpec) (s Stream, err error) {
 
 		ctx:    ctx,
 		cancel: cancel,
-		n:      n,
+		n0:     n,
 		groups: groups,
+		n:      n,
 		stats: Stats{
 			RangeRequested: d,
 		},
@@ -399,7 +400,7 @@ func (m *mgr) getReadyChunk() *chunk {
 		start, end := s.nextChunkRange()
 		chunkID := strconv.Itoa(int(s.next))
 		s.next++
-		if s.next < s.n {
+		if s.next < s.n0 {
 			heap.Push(&m.pq, s)
 		}
 
diff --git a/stream.go b/stream.go
index 5ac68ab..fd2aae1 100644
--- a/stream.go
+++ b/stream.go
@@ -16,12 +16,13 @@ type stream struct {
 	// Immutable fields.
 	ctx    context.Context    // Stream context used to parent chunk contexts
 	cancel context.CancelFunc // Cancels ctx when the stream is closed
-	n      int64              // Number of total chunks
+	n0     int64              // Number of generation 0 chunks
 	groups []*string          // Preprocessed slice for StartQuery
 
 	// Mutable fields only read/written by mgr loop goroutine.
-	next int64 // Next chunk to create
-	m    int64 // Number of chunks completed
+	next int64 // Next generation 0 chunk to create
+	m    int64 // Number of chunks completed so far
+	n    int64 // Number of chunks (may grow beyond n0 due to splitting)
 
 	// Lock controlling access to the below mutable fields.
 	lock sync.RWMutex
@@ -121,7 +122,7 @@ func (s *stream) alive() bool {
 func (s *stream) nextChunkRange() (start, end time.Time) {
 	// For a single-chunk query, the chunk range is always the query
 	// range.
-	if s.n == 1 && s.Chunk == s.End.Sub(s.Start) {
+	if s.n0 == 1 && s.Chunk == s.End.Sub(s.Start) {
 		start, end = s.Start, s.End
 		return
 	}
diff --git a/stream_test.go b/stream_test.go
index 2745812..4a9532e 100644
--- a/stream_test.go
+++ b/stream_test.go
@@ -228,7 +228,7 @@ func TestStream_NextChunkRange(t *testing.T) {
 					End:   defaultEnd.Add(time.Hour),
 					Chunk: 2*time.Hour + defaultDuration,
 				},
-				n:    1,
+				n0:   1,
 				next: 0,
 			},
 			c: chunk{