diff --git a/hardware/arduino/sam/variants/arduino_due_x/variant.cpp b/hardware/arduino/sam/variants/arduino_due_x/variant.cpp
index e60fed025..5f69d0817 100644
--- a/hardware/arduino/sam/variants/arduino_due_x/variant.cpp
+++ b/hardware/arduino/sam/variants/arduino_due_x/variant.cpp
@@ -348,8 +348,8 @@ void init( void )
   // Initialize C library
   __libc_init_array();
 
-  // Disable pull-up on every pin except RX0
-  for (int i = 1; i < PINS_COUNT; i++)
+  // Disable pull-up on every pin
+  for (int i = 0; i < PINS_COUNT; i++)
 	  digitalWrite(i, LOW);
 
   // Initialize Serial port U(S)ART pins
@@ -358,6 +358,7 @@ void init( void )
     g_APinDescription[PINS_UART].ulPinType,
     g_APinDescription[PINS_UART].ulPin,
     g_APinDescription[PINS_UART].ulPinConfiguration);
+  digitalWrite(0, HIGH); // Enable pullup for RX0
   PIO_Configure(
     g_APinDescription[PINS_USART0].pPort,
     g_APinDescription[PINS_USART0].ulPinType,