diff --git a/cores/esp8266/uart.c b/cores/esp8266/uart.c
index f2db9ae42..9294e9170 100644
--- a/cores/esp8266/uart.c
+++ b/cores/esp8266/uart.c
@@ -230,7 +230,7 @@ void uart_uninit(uart_t* uart)
         break;
     }
 
-    os_free(uart);
+    free(uart);
 }
 
 void uart_swap(uart_t* uart, int tx_pin)