diff --git a/xwords4/android/XWords4/jni/xwjni.c b/xwords4/android/XWords4/jni/xwjni.c
index 9aa025699..8f5d4b634 100644
--- a/xwords4/android/XWords4/jni/xwjni.c
+++ b/xwords4/android/XWords4/jni/xwjni.c
@@ -1104,7 +1104,7 @@ Java_org_eehouse_android_xw4_jni_XwJNI_game_1summarize
             XP_UCHAR buf[128];
             XP_U16 len = VSIZE(buf);
             if ( comms_getRelayID( comms, buf, &len ) ) {
-                XP_ASSERT( '\0' == buf[len] );
+                XP_ASSERT( '\0' == buf[len-1] ); /* failed! */
                 setString( env, jsummary, "relayID", buf );
             }
             setString( env, jsummary, "roomName", addr.u.ip_relay.invite );