diff --git a/os/hal/ports/STM32/LLD/SPIv1/hal_spi_lld.c b/os/hal/ports/STM32/LLD/SPIv1/hal_spi_lld.c
index 8baf59717..4be8cedc1 100644
--- a/os/hal/ports/STM32/LLD/SPIv1/hal_spi_lld.c
+++ b/os/hal/ports/STM32/LLD/SPIv1/hal_spi_lld.c
@@ -513,6 +513,8 @@ void spi_lld_unselect(SPIDriver *spip) {
  */
 void spi_lld_ignore(SPIDriver *spip, size_t n) {
 
+  osalDbgAssert(n < 65536, "unsupported DMA transfer size");
+
   dmaStreamSetMemory0(spip->dmarx, &dummyrx);
   dmaStreamSetTransactionSize(spip->dmarx, n);
   dmaStreamSetMode(spip->dmarx, spip->rxdmamode);
@@ -543,6 +545,8 @@ void spi_lld_ignore(SPIDriver *spip, size_t n) {
 void spi_lld_exchange(SPIDriver *spip, size_t n,
                       const void *txbuf, void *rxbuf) {
 
+  osalDbgAssert(n < 65536, "unsupported DMA transfer size");
+
   dmaStreamSetMemory0(spip->dmarx, rxbuf);
   dmaStreamSetTransactionSize(spip->dmarx, n);
   dmaStreamSetMode(spip->dmarx, spip->rxdmamode| STM32_DMA_CR_MINC);
@@ -570,6 +574,8 @@ void spi_lld_exchange(SPIDriver *spip, size_t n,
  */
 void spi_lld_send(SPIDriver *spip, size_t n, const void *txbuf) {
 
+  osalDbgAssert(n < 65536, "unsupported DMA transfer size");
+
   dmaStreamSetMemory0(spip->dmarx, &dummyrx);
   dmaStreamSetTransactionSize(spip->dmarx, n);
   dmaStreamSetMode(spip->dmarx, spip->rxdmamode);
@@ -597,6 +603,8 @@ void spi_lld_send(SPIDriver *spip, size_t n, const void *txbuf) {
  */
 void spi_lld_receive(SPIDriver *spip, size_t n, void *rxbuf) {
 
+  osalDbgAssert(n < 65536, "unsupported DMA transfer size");
+
   dmaStreamSetMemory0(spip->dmarx, rxbuf);
   dmaStreamSetTransactionSize(spip->dmarx, n);
   dmaStreamSetMode(spip->dmarx, spip->rxdmamode | STM32_DMA_CR_MINC);
diff --git a/os/hal/ports/STM32/LLD/SPIv2/hal_spi_lld.c b/os/hal/ports/STM32/LLD/SPIv2/hal_spi_lld.c
index 4512dabe8..914249fe7 100644
--- a/os/hal/ports/STM32/LLD/SPIv2/hal_spi_lld.c
+++ b/os/hal/ports/STM32/LLD/SPIv2/hal_spi_lld.c
@@ -515,6 +515,8 @@ void spi_lld_unselect(SPIDriver *spip) {
  */
 void spi_lld_ignore(SPIDriver *spip, size_t n) {
 
+  osalDbgAssert(n < 65536, "unsupported DMA transfer size");
+
   dmaStreamSetMemory0(spip->dmarx, &dummyrx);
   dmaStreamSetTransactionSize(spip->dmarx, n);
   dmaStreamSetMode(spip->dmarx, spip->rxdmamode);
@@ -545,6 +547,8 @@ void spi_lld_ignore(SPIDriver *spip, size_t n) {
 void spi_lld_exchange(SPIDriver *spip, size_t n,
                       const void *txbuf, void *rxbuf) {
 
+  osalDbgAssert(n < 65536, "unsupported DMA transfer size");
+
   dmaStreamSetMemory0(spip->dmarx, rxbuf);
   dmaStreamSetTransactionSize(spip->dmarx, n);
   dmaStreamSetMode(spip->dmarx, spip->rxdmamode | STM32_DMA_CR_MINC);
@@ -572,6 +576,8 @@ void spi_lld_exchange(SPIDriver *spip, size_t n,
  */
 void spi_lld_send(SPIDriver *spip, size_t n, const void *txbuf) {
 
+  osalDbgAssert(n < 65536, "unsupported DMA transfer size");
+
   dmaStreamSetMemory0(spip->dmarx, &dummyrx);
   dmaStreamSetTransactionSize(spip->dmarx, n);
   dmaStreamSetMode(spip->dmarx, spip->rxdmamode);
@@ -599,6 +605,8 @@ void spi_lld_send(SPIDriver *spip, size_t n, const void *txbuf) {
  */
 void spi_lld_receive(SPIDriver *spip, size_t n, void *rxbuf) {
 
+  osalDbgAssert(n < 65536, "unsupported DMA transfer size");
+
   dmaStreamSetMemory0(spip->dmarx, rxbuf);
   dmaStreamSetTransactionSize(spip->dmarx, n);
   dmaStreamSetMode(spip->dmarx, spip->rxdmamode | STM32_DMA_CR_MINC);
diff --git a/readme.txt b/readme.txt
index 1b2a50eea..bf77f32f0 100644
--- a/readme.txt
+++ b/readme.txt
@@ -179,6 +179,8 @@
        to 16.1.8).
 - HAL: Fixed invalid SDC OCR initialization value (bug #826)(backported
        to 16.1.8).
+- HAL: Fixed SPI operations silently drop length bits (bug #825)(backported
+       to 16.1.9).
 - HAL: Fixed osThreadSetPriority() returns old priority instead of a status
        code (bug #823)(backported to 16.1.8).
 - HAL: Fixed problem in rtcSTM32SetPeriodicWakeup() (bug #821)(backported