diff --git a/ip.go b/ip.go
index c672ff4..5f78fcc 100644
--- a/ip.go
+++ b/ip.go
@@ -14,7 +14,10 @@
 
 package net
 
-import "internal/bytealg"
+import (
+	"internal/bytealg"
+	"internal/itoa"
+)
 
 // IP address lengths (bytes).
 const (
@@ -533,7 +536,7 @@ func (n *IPNet) String() string {
 	if l == -1 {
 		return nn.String() + "/" + m.String()
 	}
-	return nn.String() + "/" + uitoa(uint(l))
+	return nn.String() + "/" + itoa.Uitoa(uint(l))
 }
 
 // Parse IPv4 address (d.d.d.d).
diff --git a/parse.go b/parse.go
index 2a840c8..f1f2ccb 100644
--- a/parse.go
+++ b/parse.go
@@ -64,24 +64,6 @@ func xtoi2(s string, e byte) (byte, bool) {
 	return byte(n), ok && ei == 2
 }
 
-// Convert unsigned integer to decimal string.
-func uitoa(val uint) string {
-	if val == 0 { // avoid string allocation
-		return "0"
-	}
-	var buf [20]byte // big enough for 64bit value base 10
-	i := len(buf) - 1
-	for val >= 10 {
-		q := val / 10
-		buf[i] = byte('0' + val - q*10)
-		i--
-		val = q
-	}
-	// val < 10
-	buf[i] = byte('0' + val)
-	return string(buf[i:])
-}
-
 // Convert i to a hexadecimal string. Leading zeros are not printed.
 func appendHex(dst []byte, i uint32) []byte {
 	if i == 0 {