diff --git a/libraries/AP_SerialManager/AP_SerialManager.cpp b/libraries/AP_SerialManager/AP_SerialManager.cpp
index 39e687a441..c760a7d04f 100644
--- a/libraries/AP_SerialManager/AP_SerialManager.cpp
+++ b/libraries/AP_SerialManager/AP_SerialManager.cpp
@@ -649,18 +649,6 @@ AP_HAL::UARTDriver *AP_SerialManager::get_serial_by_id(uint8_t id)
     return nullptr;
 }
 
-// set_blocking_writes_all - sets block_writes on or off for all serial channels
-void AP_SerialManager::set_blocking_writes_all(bool blocking)
-{
-    // set block_writes for all initialised serial ports
-    for (uint8_t i=0; i<SERIALMANAGER_NUM_PORTS; i++) {
-        auto *uart = hal.serial(i);
-        if (uart != nullptr) {
-            uart->set_blocking_writes(blocking);
-        }
-    }
-}
-
 /*
  *  map from a 16 bit EEPROM baud rate to a real baud rate.  For
  *  stm32-based boards we can do 1.5MBit, although 921600 is more
diff --git a/libraries/AP_SerialManager/AP_SerialManager.h b/libraries/AP_SerialManager/AP_SerialManager.h
index c6ab5f9667..d4f2f92b2f 100644
--- a/libraries/AP_SerialManager/AP_SerialManager.h
+++ b/libraries/AP_SerialManager/AP_SerialManager.h
@@ -201,9 +201,6 @@ public:
     // find_portnum - find port number (SERIALn index) for a protocol and instance, -1 for not found
     int8_t find_portnum(enum SerialProtocol protocol, uint8_t instance) const;
 
-    // set_blocking_writes_all - sets block_writes on or off for all serial channels
-    void set_blocking_writes_all(bool blocking);
-
     // get the passthru ports if enabled
     bool get_passthru(AP_HAL::UARTDriver *&port1, AP_HAL::UARTDriver *&port2, uint8_t &timeout_s,
                       uint32_t &baud1, uint32_t &baud2) const;