diff --git a/core/java/android/net/StaticIpConfiguration.java b/core/java/android/net/StaticIpConfiguration.java
index 0728d83..14dbca0 100644
--- a/core/java/android/net/StaticIpConfiguration.java
+++ b/core/java/android/net/StaticIpConfiguration.java
@@ -134,7 +134,7 @@
      * route to the gateway as well. This configuration is arguably invalid, but it used to work
      * in K and earlier, and other OSes appear to accept it.
      */
-    public @NonNull List<RouteInfo> getRoutes(String iface) {
+    public @NonNull List<RouteInfo> getRoutes(@Nullable String iface) {
         List<RouteInfo> routes = new ArrayList<RouteInfo>(3);
         if (ipAddress != null) {
             RouteInfo connectedRoute = new RouteInfo(ipAddress, null, iface);