diff --git a/os/hal/src/hal_uart.c b/os/hal/src/hal_uart.c
index 8df77adb5..89276f28f 100644
--- a/os/hal/src/hal_uart.c
+++ b/os/hal/src/hal_uart.c
@@ -384,7 +384,7 @@ msg_t uartSendTimeout(UARTDriver *uartp, size_t *np,
   /* Waiting for result.*/
   msg = osalThreadSuspendTimeoutS(&uartp->threadtx, timeout);
   if (msg != MSG_OK) {
-    *np = uartStopSendI(uartp);
+    *np -= uartStopSendI(uartp);
   }
   osalSysUnlock();
 
@@ -475,7 +475,7 @@ msg_t uartReceiveTimeout(UARTDriver *uartp, size_t *np,
   /* Waiting for result.*/
   msg = osalThreadSuspendTimeoutS(&uartp->threadrx, timeout);
   if (msg != MSG_OK) {
-    *np = uartStopReceiveI(uartp);
+    *np -= uartStopReceiveI(uartp);
   }
   osalSysUnlock();
 
diff --git a/readme.txt b/readme.txt
index ec4d0951b..7703f3348 100644
--- a/readme.txt
+++ b/readme.txt
@@ -89,6 +89,7 @@
 *****************************************************************************
 
 *** 17.6.1 ***
+- HAL: Fixed error in uartReceiveTimeout() and uartSendTimeout() (bug #883).
 - HAL: Fixed TIMx DBL field macro broken (bug #880).
 - HAL: Fixed STM32 SPI problem in spi_lld_start() (bug #879).
 - HAL: Fixed invalid STM32 CAN3 filters initialization (bug #878).