diff --git a/core/java/android/net/VpnService.java b/core/java/android/net/VpnService.java
index fb5263d9f13d5..65d3f2b27673f 100644
--- a/core/java/android/net/VpnService.java
+++ b/core/java/android/net/VpnService.java
@@ -329,7 +329,7 @@ public class VpnService extends Service {
                 throw new IllegalArgumentException("Bad address");
             }
 
-            mAddresses.append(String.format(" %s/%d", address.getHostAddress(), prefixLength));
+            mAddresses.append(' ' + address.getHostAddress() + '/' +  prefixLength);
             return this;
         }