diff --git a/xwords4/relay/udpack.cpp b/xwords4/relay/udpack.cpp
index 297032c7c..75762b829 100644
--- a/xwords4/relay/udpack.cpp
+++ b/xwords4/relay/udpack.cpp
@@ -23,13 +23,17 @@
 UDPAckTrack* UDPAckTrack::s_self = NULL;
 
 
+/* static*/ bool
+UDPAckTrack::shouldAck( XWRelayReg cmd )
+{
+    return ( XWPDEV_ACK != cmd && XWPDEV_ALERT != cmd );
+}
+
 /* static*/ uint32_t
 UDPAckTrack::nextPacketID( XWRelayReg cmd )
 {
-    uint32_t result;
-    if ( XWPDEV_ACK == cmd || XWPDEV_ALERT == cmd ) {
-        result = 0;
-    } else {
+    uint32_t result = 0;
+    if ( shouldAck( cmd ) ) {
         result = get()->nextPacketIDImpl();
     }
     return result;
@@ -115,9 +119,10 @@ UDPAckTrack::threadProc()
                 }
                 string_printf( leaked, ", " );
             }
-            logf( XW_LOGERROR, "these packets leaked: %s", leaked.c_str() );
+            logf( XW_LOGERROR, "%s: these packets leaked: %s", __func__, 
+                  leaked.c_str() );
         } else {
-            logf( XW_LOGINFO, "no packets leaked" );
+            logf( XW_LOGINFO, "%s: no packets leaked", __func__ );
         }
     }
     return NULL;
diff --git a/xwords4/relay/udpack.h b/xwords4/relay/udpack.h
index 5df604154..ee94a046b 100644
--- a/xwords4/relay/udpack.h
+++ b/xwords4/relay/udpack.h
@@ -33,6 +33,7 @@ class UDPAckTrack {
  public:
     static uint32_t nextPacketID( XWRelayReg cmd );
     static void recordAck( uint32_t packetID ); 
+    static bool shouldAck( XWRelayReg cmd );
 
  private:
     static UDPAckTrack* get();
diff --git a/xwords4/relay/xwrelay.cpp b/xwords4/relay/xwrelay.cpp
index e281cf1da..52a8f04e1 100644
--- a/xwords4/relay/xwrelay.cpp
+++ b/xwords4/relay/xwrelay.cpp
@@ -1293,6 +1293,18 @@ msgToStr( XWRelayReg msg )
 
 }
 
+static void
+ackPacketIf( const UDPHeader* header, const AddrInfo* addr )
+{
+    if ( UDPAckTrack::shouldAck( header->cmd ) ) {
+        uint32_t packetID = header->packetID;
+        logf( XW_LOGINFO, "acking packet %d", packetID );
+        packetID = htonl( packetID );
+        send_via_udp( addr->socket(), addr->sockaddr(), XWPDEV_ACK, 
+                      &packetID, sizeof(packetID), NULL );
+    }
+}
+
 static void
 udp_thread_proc( UdpThreadClosure* utc )
 {
@@ -1302,6 +1314,7 @@ udp_thread_proc( UdpThreadClosure* utc )
     UDPHeader header;
     if ( getHeader( &ptr, end, &header ) ) {
         logf( XW_LOGINFO, "%s(msg=%s)", __func__, msgToStr( header.cmd ) );
+        ackPacketIf( &header, utc->addr() );
         switch( header.cmd ) {
         case XWPDEV_REG: {
             DevIDType typ = (DevIDType)*ptr++;
@@ -1375,6 +1388,7 @@ udp_thread_proc( UdpThreadClosure* utc )
         case XWPDEV_ACK: {
             uint32_t packetID;
             if ( getNetLong( &ptr, end, &packetID ) ) {
+                logf( XW_LOGINFO, "ack for packet %d", packetID );
                 UDPAckTrack::recordAck( packetID );
             }
             break;