diff --git a/cores/rp2040/SerialUART.cpp b/cores/rp2040/SerialUART.cpp
index 0af70afe..ba8d183f 100644
--- a/cores/rp2040/SerialUART.cpp
+++ b/cores/rp2040/SerialUART.cpp
@@ -161,7 +161,7 @@ void SerialUART::flush() {
     if (!_running || !m) {
         return;
     }
-    uart_default_tx_wait_blocking();
+    uart_tx_wait_blocking(_uart);
 }
 
 size_t SerialUART::write(uint8_t c) {