diff --git a/main.go b/main.go
index 6cefcdede574e69abca3373cb3b069c7a2401640..bcbf8c8db0947844febfd25c06263ce11a6e9351 100644
--- a/main.go
+++ b/main.go
@@ -18,7 +18,7 @@ var (
 )
 
 var (
-	in []byte
+	in  []byte
 	out io.Writer
 )
 
@@ -73,7 +73,7 @@ func main() {
 			c++
 		}
 	}
-	out, err = os.OpenFile("output.png", os.O_WRONLY|os.O_CREATE, 0644)
+	out, err = os.OpenFile("output.png", os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
 	if err != nil {
 		println("Error while opening output,", err)
 		os.Exit(1)