diff

diff --git a/signal.go b/signal.go
index 97572b1..3faf912 100644
--- a/signal.go
+++ b/signal.go
@@ -17,25 +17,20 @@ func (e ErrSignal) Error() string {
 	return fmt.Sprintf("got signal: %s", e.Signal)
 }
 
-// signalNotify is the signal notify function.
-// It is used in a variable for testing purposes.
-var signalNotify = signal.Notify
-
 // WithSignal returns a context which is done when an OS signal is sent.
 // parent is a parent context to wrap.
-// sigWhiteList is a list of signals to listen on. According to the
-// signal.Notify behavior, an empty list will listen to any OS signal.
+// sigWhiteList is a list of signals to listen on.
+// According to the signal.Notify behavior, an empty list will listen
+// to any OS signal.
 // If an OS signal closed this context, ErrSignal will be returned in
-// the Err() method.
+// the Err() method of the returned context.
 // This method creates the signal channel and invokes a goroutine.
 func WithSignal(parent context.Context, sigWhiteList ...os.Signal) context.Context {
-	sig := make(chan os.Signal, 1)
-	signalNotify(sig, sigWhiteList...)
-	s := &signalCtx{
+	s := &signalContext{
 		Context: parent,
 		done:    make(chan struct{}),
 	}
-	go s.watch(sig)
+	go s.watch(sigWhiteList)
 	return s
 }
 
@@ -52,21 +47,32 @@ func Interrupt() context.Context {
 	return WithSignal(context.Background(), os.Interrupt)
 }
 
-type signalCtx struct {
+// signalContext implements the context interface.
+// It is being cancelled with OS signal cancellation.
+type signalContext struct {
 	context.Context
 	done chan struct{}
 	err  error
 }
 
-func (s *signalCtx) Done() <-chan struct{} {
+func (s *signalContext) Done() <-chan struct{} {
 	return s.done
 }
 
-func (s *signalCtx) Err() error {
+func (s *signalContext) Err() error {
 	return s.err
 }
 
-func (s *signalCtx) watch(sigCh <-chan os.Signal) {
+// signalNotify is the signal notify function.
+// It is used in a variable for testing purposes.
+var signalNotify = signal.Notify
+
+// watch should be run in a goroutine when creating a signalContext.
+// It
+func (s *signalContext) watch(sigWhiteList []os.Signal) {
+	sigCh := make(chan os.Signal, 1)
+	signalNotify(sigCh, sigWhiteList...)
+
 	select {
 	case <-s.Context.Done():
 		s.err = s.Context.Err()