diff --git a/cores/arduino/SerialObj1.cpp b/cores/arduino/SerialObj1.cpp
index 11fb873f7..1051a8d15 100644
--- a/cores/arduino/SerialObj1.cpp
+++ b/cores/arduino/SerialObj1.cpp
@@ -1,5 +1,9 @@
 #include "Serial.h"
 
 #if SERIAL_HOWMANY > 0
+#if defined(UART1_RTS_PIN) && defined(UART1_CTS_PIN)
+UART _UART1_(UART1_TX_PIN, UART1_RX_PIN, UART1_RTS_PIN, UART1_CTS_PIN);
+#else
 UART _UART1_(UART1_TX_PIN, UART1_RX_PIN);
+#endif
 #endif
\ No newline at end of file
diff --git a/cores/arduino/SerialObj2.cpp b/cores/arduino/SerialObj2.cpp
index 5497e42e4..7d9597ed5 100644
--- a/cores/arduino/SerialObj2.cpp
+++ b/cores/arduino/SerialObj2.cpp
@@ -1,5 +1,9 @@
 #include "Serial.h"
 
 #if SERIAL_HOWMANY > 1
+#if defined(UART2_RTS_PIN) && defined(UART2_CTS_PIN)
+UART _UART2_(UART2_TX_PIN, UART2_RX_PIN, UART2_RTS_PIN, UART2_CTS_PIN);
+#else
 UART _UART2_(UART2_TX_PIN, UART2_RX_PIN);
+#endif
 #endif
\ No newline at end of file
diff --git a/cores/arduino/SerialObj3.cpp b/cores/arduino/SerialObj3.cpp
index 2f083d49b..4977ff8c9 100644
--- a/cores/arduino/SerialObj3.cpp
+++ b/cores/arduino/SerialObj3.cpp
@@ -1,13 +1,25 @@
 #include "Serial.h"
 
 #if SERIAL_HOWMANY > 2
+#if defined(UART3_RTS_PIN) && defined(UART3_CTS_PIN)
+UART _UART3_(UART3_TX_PIN, UART3_RX_PIN, UART3_RTS_PIN, UART3_CTS_PIN);
+#else
 UART _UART3_(UART3_TX_PIN, UART3_RX_PIN);
 #endif
+#endif
 
 #if SERIAL_HOWMANY > 3
+#if defined(UART4_RTS_PIN) && defined(UART4_CTS_PIN)
+UART _UART4_(UART4_TX_PIN, UART4_RX_PIN, UART4_RTS_PIN, UART4_CTS_PIN);
+#else
 UART _UART4_(UART4_TX_PIN, UART4_RX_PIN);
 #endif
+#endif
 
 #if SERIAL_HOWMANY > 4
+#if defined(UART5_RTS_PIN) && defined(UART5_CTS_PIN)
 UART _UART5_(UART5_TX_PIN, UART5_RX_PIN, UART5_RTS_PIN, UART5_CTS_PIN);
+#else
+UART _UART5_(UART5_TX_PIN, UART5_RX_PIN);
+#endif
 #endif
\ No newline at end of file