diff --git a/content/concurrency/channels.go b/content/concurrency/channels.go
index a3e92c2..60fc324 100644
--- a/content/concurrency/channels.go
+++ b/content/concurrency/channels.go
@@ -4,20 +4,20 @@
 
 import "fmt"
 
-func sum(a []int, c chan int) {
+func sum(s []int, c chan int) {
 	sum := 0
-	for _, v := range a {
+	for _, v := range s {
 		sum += v
 	}
 	c <- sum // send sum to c
 }
 
 func main() {
-	a := []int{7, 2, 8, -9, 4, 0}
+	s := []int{7, 2, 8, -9, 4, 0}
 
 	c := make(chan int)
-	go sum(a[:len(a)/2], c)
-	go sum(a[len(a)/2:], c)
+	go sum(s[:len(s)/2], c)
+	go sum(s[len(s)/2:], c)
 	x, y := <-c, <-c // receive from c
 
 	fmt.Println(x, y, x+y)