diff --git a/infinitime.go b/infinitime.go
index d0edb1d..d92b189 100644
--- a/infinitime.go
+++ b/infinitime.go
@@ -725,7 +725,7 @@ func (i *Device) SetTimezone(t time.Time) error {
 	dst := 0
 	if t.IsDST() {
 		dst = 3600
-		offset = offset - 3600
+		offset -= 3600
 	}
 	buf := &bytes.Buffer{}
 	binary.Write(buf, binary.LittleEndian, uint8(offset / 3600 * 4))