diff --git a/doc/code.html b/doc/code.html
index f64dd6a2ad1..2bf50601e45 100644
--- a/doc/code.html
+++ b/doc/code.html
@@ -295,9 +295,9 @@ package newmath
 
 // Sqrt returns an approximation to the square root of x.
 func Sqrt(x float64) float64 {
-	z := 0.0
+	z := 1.0
 	for i := 0; i < 1000; i++ {
-		z -= (z*z - x) / (2 * x)
+		z -= (z*z - x) / (2 * z)
 	}
 	return z
 }