diff --git a/README.md b/README.md
index 80efb7a..0468c33 100644
--- a/README.md
+++ b/README.md
@@ -52,14 +52,14 @@ import (
 
 var sum int32
 
-func myFunc(i interface{}) error {
+func myFunc(i interface{}) {
 	n := i.(int32)
 	atomic.AddInt32(&sum, n)
 	fmt.Printf("run with %d\n", n)
 	return nil
 }
 
-func demoFunc() error {
+func demoFunc() {
 	time.Sleep(10 * time.Millisecond)
 	fmt.Println("Hello World!")
 	return nil
diff --git a/README_ZH.md b/README_ZH.md
index f7ab2d6..4cf9541 100644
--- a/README_ZH.md
+++ b/README_ZH.md
@@ -51,14 +51,14 @@ import (
 
 var sum int32
 
-func myFunc(i interface{}) error {
+func myFunc(i interface{}) {
 	n := i.(int32)
 	atomic.AddInt32(&sum, n)
 	fmt.Printf("run with %d\n", n)
 	return nil
 }
 
-func demoFunc() error {
+func demoFunc() {
 	time.Sleep(10 * time.Millisecond)
 	fmt.Println("Hello World!")
 	return nil
diff --git a/examples/main.go b/examples/main.go
index 521172c..be8dfc3 100644
--- a/examples/main.go
+++ b/examples/main.go
@@ -33,14 +33,14 @@ import (
 
 var sum int32
 
-func myFunc(i interface{}) error {
+func myFunc(i interface{}) {
 	n := i.(int32)
 	atomic.AddInt32(&sum, n)
 	fmt.Printf("run with %d\n", n)
 	return nil
 }
 
-func demoFunc() error {
+func demoFunc() {
 	time.Sleep(10 * time.Millisecond)
 	fmt.Println("Hello World!")
 	return nil