diff --git a/Tethering/jni/com_android_networkstack_tethering_BpfUtils.cpp b/Tethering/jni/com_android_networkstack_tethering_BpfUtils.cpp
index 1611f9d..2fb5985 100644
--- a/Tethering/jni/com_android_networkstack_tethering_BpfUtils.cpp
+++ b/Tethering/jni/com_android_networkstack_tethering_BpfUtils.cpp
@@ -183,7 +183,7 @@
             return false;
         default:
             jniThrowExceptionFmt(env, "java/io/IOException",
-                                 "Unknown hardware address type %s on interface %s", rv,
+                                 "Unknown hardware address type %d on interface %s", rv,
                                  interface.c_str());
             return false;
     }