diff --git a/libraries/tests/mbed/serial_nc_rx/main.cpp b/libraries/tests/mbed/serial_nc_rx/main.cpp
index f97e114378..5f1ebc9dd8 100644
--- a/libraries/tests/mbed/serial_nc_rx/main.cpp
+++ b/libraries/tests/mbed/serial_nc_rx/main.cpp
@@ -2,31 +2,37 @@
 #include "test_env.h"
 
 int main() {
+    Serial *pc = new Serial(USBTX, USBRX);
+
     MBED_HOSTTEST_TIMEOUT(20);
     MBED_HOSTTEST_SELECT(serial_nc_rx_auto);
     MBED_HOSTTEST_DESCRIPTION(Serial NC RX);
     MBED_HOSTTEST_START("MBED_37");
 
-    Serial *pc = new Serial(NC, USBRX);
-
     char c = pc->getc();
 
-    delete pc;
 
-    // This should be true
-    if (c == 'E') {
-      Serial *pc = new Serial(USBTX, NC);
+    // This should be true, sync the start of test
+    if (c == 'S') {
+        pc->printf("RX OK - Start NC test\r\n");
 
-      pc->printf("RX OK - Expected\r\n");
+        // disconnect TX and  get char
+        delete pc;
+        pc = new Serial(NC, USBRX);
+        c = pc->getc();
+        if (c == 'E') {
+            // ok disconnect Rx and answer to host
+            delete pc;
+            pc = new Serial(USBTX, NC);
+            pc->printf("RX OK - Expected\r\n");
 
-      c = pc->getc();
-
-      // This should be false/not get here
-      if (c == 'U') {
-        pc->printf("RX OK - Unexpected\r\n");
-      }
-
-      delete pc;
+            c = pc->getc();
+            // This should be false/not get here
+            if (c == 'U') {
+                pc->printf("RX OK - Unexpected\r\n");
+            }
+        }
+        delete pc;
     }
 
     while (1) {
diff --git a/libraries/tests/mbed/serial_nc_tx/main.cpp b/libraries/tests/mbed/serial_nc_tx/main.cpp
index 95e9a311b0..8dae9e50bc 100644
--- a/libraries/tests/mbed/serial_nc_tx/main.cpp
+++ b/libraries/tests/mbed/serial_nc_tx/main.cpp
@@ -2,13 +2,14 @@
 #include "test_env.h"
 
 int main() {
+    Serial *pc = new Serial(USBTX, USBRX);
+
     MBED_HOSTTEST_TIMEOUT(20);
     MBED_HOSTTEST_SELECT(serial_nc_tx_auto);
     MBED_HOSTTEST_DESCRIPTION(Serial NC TX);
     MBED_HOSTTEST_START("MBED_38");
 
     // Wait until we receive start signal from host test
-    Serial *pc = new Serial(USBTX, USBRX);
     char c = pc->getc();
     delete pc;
 
diff --git a/workspace_tools/host_tests/serial_nc_rx_auto.py b/workspace_tools/host_tests/serial_nc_rx_auto.py
index cd12ebe611..59975dbeb7 100644
--- a/workspace_tools/host_tests/serial_nc_rx_auto.py
+++ b/workspace_tools/host_tests/serial_nc_rx_auto.py
@@ -25,6 +25,29 @@ class SerialNCRXTest():
 
     def test(self, selftest):
         selftest.mbed.flush();
+        # Wait 0.5 seconds to ensure mbed is listening
+        time.sleep(0.5)
+
+        #handshake with target to sync test start
+        selftest.mbed.serial_write("S");
+
+        strip_chars = string.whitespace + "\0"
+
+        out_str = selftest.mbed.serial_readline()
+
+        if not out_str:
+            selftest.notify("HOST: No output detected")
+            return selftest.RESULT_IO_SERIAL
+
+        out_str_stripped = out_str.strip(strip_chars)
+
+        if out_str_stripped != "RX OK - Start NC test":
+            selftest.notify("HOST: Unexpected output. Expected 'RX OK - Expected' but received '%s'" % out_str_stripped)
+            return selftest.RESULT_FAILURE
+
+        # Wait 0.5 seconds to ensure mbed is listening
+        time.sleep(0.5)
+
         selftest.mbed.serial_write("E");
 
         strip_chars = string.whitespace + "\0"
diff --git a/workspace_tools/host_tests/serial_nc_tx_auto.py b/workspace_tools/host_tests/serial_nc_tx_auto.py
index 549bbecb3c..707c4763af 100644
--- a/workspace_tools/host_tests/serial_nc_tx_auto.py
+++ b/workspace_tools/host_tests/serial_nc_tx_auto.py
@@ -25,6 +25,9 @@ class SerialNCTXTest():
 
     def test(self, selftest):
         selftest.mbed.flush();
+        # Wait 0.5 seconds to ensure mbed is listening
+        time.sleep(0.5)
+
         selftest.mbed.serial_write("S");
 
         strip_chars = string.whitespace + "\0"