diff --git a/pkg/model/word2vec/model.go b/pkg/model/word2vec/model.go
index e0e29c6..818d9ef 100644
--- a/pkg/model/word2vec/model.go
+++ b/pkg/model/word2vec/model.go
@@ -77,15 +77,23 @@ func (mod *skipGram) trainOne(
 	}
 }
 
+type cbowToken struct {
+	agg []float64
+	tmp []float64
+}
+
 type cbow struct {
-	ch     chan []float64
+	ch     chan cbowToken
 	window int
 }
 
 func newCbow(opts Options) mod {
-	ch := make(chan []float64, opts.Goroutines*2)
+	ch := make(chan cbowToken, opts.Goroutines)
 	for i := 0; i < opts.Goroutines; i++ {
-		ch <- make([]float64, opts.Dim)
+		ch <- cbowToken{
+			agg: make([]float64, opts.Dim),
+			tmp: make([]float64, opts.Dim),
+		}
 	}
 	return &cbow{
 		ch:     ch,
@@ -100,10 +108,11 @@ func (mod *cbow) trainOne(
 	param *matrix.Matrix,
 	optimizer optimizer,
 ) {
-	agg, tmp := <-mod.ch, <-mod.ch
+	token := <-mod.ch
+	agg, tmp := token.agg, token.tmp
 	defer func() {
-		mod.ch <- agg
-		mod.ch <- tmp
+		token := cbowToken{agg, tmp}
+		mod.ch <- token
 	}()
 	for i := 0; i < len(agg); i++ {
 		agg[i], tmp[i] = 0, 0