diff --git a/serial_link/protocol/frame_router.c b/serial_link/protocol/frame_router.c
index c61c50ebd68..890ebbe9ea3 100644
--- a/serial_link/protocol/frame_router.c
+++ b/serial_link/protocol/frame_router.c
@@ -33,7 +33,9 @@ void router_set_master(bool master) {
 
 void route_incoming_frame(uint8_t link, uint8_t* data, uint16_t size){
     if (is_master) {
-        transport_recv_frame(data[size-1], data, size - 1);
+        if (link == DOWN_LINK) {
+            transport_recv_frame(data[size-1], data, size - 1);
+        }
     }
     else {
         if (link == UP_LINK) {
@@ -52,11 +54,15 @@ void route_incoming_frame(uint8_t link, uint8_t* data, uint16_t size){
 
 void router_send_frame(uint8_t destination, uint8_t* data, uint16_t size) {
     if (destination == 0) {
-        data[size] = 1;
-        validator_send_frame(UP_LINK, data, size + 1);
+        if (!is_master) {
+            data[size] = 1;
+            validator_send_frame(UP_LINK, data, size + 1);
+        }
     }
     else {
-        data[size] = destination;
-        validator_send_frame(DOWN_LINK, data, size + 1);
+        if (is_master) {
+            data[size] = destination;
+            validator_send_frame(DOWN_LINK, data, size + 1);
+        }
     }
 }
diff --git a/serial_link/tests/frame_router_tests.c b/serial_link/tests/frame_router_tests.c
index 6b00aca6777..0b0ea6e7f48 100644
--- a/serial_link/tests/frame_router_tests.c
+++ b/serial_link/tests/frame_router_tests.c
@@ -174,7 +174,6 @@ Ensure(FrameRouter, first_link_sends_to_master) {
 }
 
 Ensure(FrameRouter, second_link_sends_to_master) {
-    printf("Second to master start\n");
     frame_buffer_t data;
     data.data = 0xAB7055BB;
     activate_router(2);
@@ -195,3 +194,38 @@ Ensure(FrameRouter, second_link_sends_to_master) {
     assert_that(router_buffers[0].send_buffers[DOWN_LINK].sent_data_size, is_equal_to(0));
     assert_that(router_buffers[0].send_buffers[UP_LINK].sent_data_size, is_equal_to(0));
 }
+
+Ensure(FrameRouter, master_sends_to_master_does_nothing) {
+    frame_buffer_t data;
+    data.data = 0xAB7055BB;
+    activate_router(0);
+    router_send_frame(0, (uint8_t*)&data, 4);
+    assert_that(router_buffers[0].send_buffers[UP_LINK].sent_data_size, is_equal_to(0));
+    assert_that(router_buffers[0].send_buffers[DOWN_LINK].sent_data_size, is_equal_to(0));
+}
+
+Ensure(FrameRouter, link_sends_to_other_link_does_nothing) {
+    frame_buffer_t data;
+    data.data = 0xAB7055BB;
+    activate_router(1);
+    router_send_frame(2, (uint8_t*)&data, 4);
+    assert_that(router_buffers[1].send_buffers[UP_LINK].sent_data_size, is_equal_to(0));
+    assert_that(router_buffers[1].send_buffers[DOWN_LINK].sent_data_size, is_equal_to(0));
+}
+
+Ensure(FrameRouter, master_receives_on_uplink_does_nothing) {
+    frame_buffer_t data;
+    data.data = 0xAB7055BB;
+    activate_router(1);
+    router_send_frame(0, (uint8_t*)&data, 4);
+    assert_that(router_buffers[1].send_buffers[UP_LINK].sent_data_size, is_greater_than(0));
+    assert_that(router_buffers[1].send_buffers[DOWN_LINK].sent_data_size, is_equal_to(0));
+
+    never_expect(transport_recv_frame);
+    activate_router(0);
+    receive_data(UP_LINK,
+        router_buffers[1].send_buffers[UP_LINK].sent_data,
+        router_buffers[1].send_buffers[UP_LINK].sent_data_size);
+    assert_that(router_buffers[0].send_buffers[UP_LINK].sent_data_size, is_equal_to(0));
+    assert_that(router_buffers[0].send_buffers[DOWN_LINK].sent_data_size, is_equal_to(0));
+}