diff --git a/src/main.go b/src/main.go
index 0ea8a06..03b0c9e 100644
--- a/src/main.go
+++ b/src/main.go
@@ -7,6 +7,7 @@ import (
 	_ "image/png"
 	"os"
 	"strings"
+	"sync"
 )
 
 func main() {