diff --git a/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11CXX/serial_api.c b/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11CXX/serial_api.c
index 6b12c50345..18b1bd9a7e 100644
--- a/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11CXX/serial_api.c
+++ b/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11CXX/serial_api.c
@@ -249,12 +249,6 @@ int serial_getc(serial_t *obj) {
 void serial_putc(serial_t *obj, int c) {
     while (!serial_writable(obj));
     obj->uart->THR = c;
-    
-#warning TODO(@toyowata): need to fix a full-duplex bug? https://mbed.org/forum/bugs-suggestions/topic/4473/
-    uint32_t lsr = obj->uart->LSR;
-    lsr = lsr;
-    uint32_t thr = obj->uart->THR;
-    thr = thr;
 }
 
 int serial_readable(serial_t *obj) {
diff --git a/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11UXX/serial_api.c b/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11UXX/serial_api.c
index ec62bda434..637f946baa 100644
--- a/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11UXX/serial_api.c
+++ b/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC11UXX/serial_api.c
@@ -247,11 +247,6 @@ int serial_getc(serial_t *obj) {
 void serial_putc(serial_t *obj, int c) {
     while (!serial_writable(obj));
     obj->uart->THR = c;
-    
-    uint32_t lsr = obj->uart->LSR;
-    lsr = lsr;
-    uint32_t thr = obj->uart->THR;
-    thr = thr;
 }
 
 int serial_readable(serial_t *obj) {
diff --git a/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC13XX/serial_api.c b/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC13XX/serial_api.c
index af61d230bb..7791f05af0 100644
--- a/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC13XX/serial_api.c
+++ b/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC13XX/serial_api.c
@@ -247,11 +247,6 @@ int serial_getc(serial_t *obj) {
 void serial_putc(serial_t *obj, int c) {
     while (!serial_writable(obj));
     obj->uart->THR = c;
-    
-    uint32_t lsr = obj->uart->LSR;
-    lsr = lsr;
-    uint32_t thr = obj->uart->THR;
-    thr = thr;
 }
 
 int serial_readable(serial_t *obj) {
diff --git a/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC176X/serial_api.c b/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC176X/serial_api.c
index f62fcaab63..708b22763a 100644
--- a/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC176X/serial_api.c
+++ b/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC176X/serial_api.c
@@ -283,11 +283,6 @@ int serial_getc(serial_t *obj) {
 void serial_putc(serial_t *obj, int c) {
     while (!serial_writable(obj));
     obj->uart->THR = c;
-    
-    uint32_t lsr = obj->uart->LSR;
-    lsr = lsr;
-    uint32_t thr = obj->uart->THR;
-    thr = thr;
 }
 
 int serial_readable(serial_t *obj) {
diff --git a/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC23XX/serial_api.c b/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC23XX/serial_api.c
index f62fcaab63..708b22763a 100644
--- a/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC23XX/serial_api.c
+++ b/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC23XX/serial_api.c
@@ -283,11 +283,6 @@ int serial_getc(serial_t *obj) {
 void serial_putc(serial_t *obj, int c) {
     while (!serial_writable(obj));
     obj->uart->THR = c;
-    
-    uint32_t lsr = obj->uart->LSR;
-    lsr = lsr;
-    uint32_t thr = obj->uart->THR;
-    thr = thr;
 }
 
 int serial_readable(serial_t *obj) {
diff --git a/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC408X/serial_api.c b/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC408X/serial_api.c
index a59876bcd3..d65416a942 100644
--- a/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC408X/serial_api.c
+++ b/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC408X/serial_api.c
@@ -276,11 +276,6 @@ int serial_getc(serial_t *obj) {
 void serial_putc(serial_t *obj, int c) {
     while (!serial_writable(obj));
     obj->uart->THR = c;
-    
-    uint32_t lsr = obj->uart->LSR;
-    lsr = lsr;
-    uint32_t thr = obj->uart->THR;
-    thr = thr;
 }
 
 int serial_readable(serial_t *obj) {
diff --git a/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC43XX/serial_api.c b/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC43XX/serial_api.c
index 2ab2c4b6e6..a7842e6a59 100644
--- a/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC43XX/serial_api.c
+++ b/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC43XX/serial_api.c
@@ -257,11 +257,6 @@ int serial_getc(serial_t *obj) {
 void serial_putc(serial_t *obj, int c) {
     while (!serial_writable(obj));
     obj->uart->THR = c;
-    
-    uint32_t lsr = obj->uart->LSR;
-    lsr = lsr;
-    uint32_t thr = obj->uart->THR;
-    thr = thr;
 }
 
 int serial_readable(serial_t *obj) {