diff --git a/cksum.go b/cksum.go
index bf5c76c..203916e 100644
--- a/cksum.go
+++ b/cksum.go
@@ -10,7 +10,7 @@ const posixPolynomial uint32 = 0x04C11DB7
 func cksum(r io.Reader) (uint32, int, error) {
 	in := bufio.NewReader(r)
 	count := 0
-	var sum uint32 = 0
+	var sum uint32
 	f := func(b byte) {
 		for i := 7; i >= 0; i-- {
 			msb := sum & (1 << 31)