diff --git a/src/pkg/hash/adler32/adler32.go b/src/pkg/hash/adler32/adler32.go
index f13a937..84943d9 100644
--- a/src/pkg/hash/adler32/adler32.go
+++ b/src/pkg/hash/adler32/adler32.go
@@ -43,8 +43,8 @@
 
 // Add p to the running checksum a, b.
 func update(a, b uint32, p []byte) (aa, bb uint32) {
-	for i := 0; i < len(p); i++ {
-		a += uint32(p[i])
+	for _, pi := range p {
+		a += uint32(pi)
 		b += a
 		// invariant: a <= b
 		if b > (0xffffffff-255)/2 {
diff --git a/src/pkg/hash/adler32/adler32_test.go b/src/pkg/hash/adler32/adler32_test.go
index ffa5569..01f931c 100644
--- a/src/pkg/hash/adler32/adler32_test.go
+++ b/src/pkg/hash/adler32/adler32_test.go
@@ -5,6 +5,7 @@
 package adler32
 
 import (
+	"bytes"
 	"io"
 	"testing"
 )
@@ -61,3 +62,16 @@
 		}
 	}
 }
+
+func BenchmarkGolden(b *testing.B) {
+	b.StopTimer()
+	c := New()
+	var buf bytes.Buffer
+	for _, g := range golden {
+		buf.Write([]byte(g.in))
+	}
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		c.Write(buf.Bytes())
+	}
+}