diff --git a/Tethering/jni/com_android_networkstack_tethering_BpfUtils.cpp b/Tethering/jni/com_android_networkstack_tethering_BpfUtils.cpp
index 1611f9d514c9118578edb09ad25aa634417c4f7d..2fb59858e4573d7cdecf1eacfb57052069d8598f 100644
--- a/Tethering/jni/com_android_networkstack_tethering_BpfUtils.cpp
+++ b/Tethering/jni/com_android_networkstack_tethering_BpfUtils.cpp
@@ -183,7 +183,7 @@ static jboolean com_android_networkstack_tethering_BpfUtils_isEthernet(JNIEnv* e
             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;
     }