diff --git a/cmd/convergents.go b/cmd/convergents.go
index 7d5cd35..7d63c1d 100644
--- a/cmd/convergents.go
+++ b/cmd/convergents.go
@@ -23,7 +23,7 @@ import (
 	"github.com/spf13/cobra"
 )
 
-func cycle(seq []*big.Int) chan *big.Int {
+func cycle(seq []*big.Int) <-chan *big.Int {
 	ch := make(chan *big.Int)
 	n := len(seq)
 	go func() {
@@ -35,7 +35,7 @@ func cycle(seq []*big.Int) chan *big.Int {
 	return ch
 }
 
-func gaussianBrackets(x, xprev *big.Int, ch chan *big.Int) chan *big.Int {
+func gaussianBrackets(x, xprev *big.Int, ch <-chan *big.Int) <-chan *big.Int {
 	out := make(chan *big.Int)
 
 	go func() {