diff --git a/can-halal.c b/can-halal.c
index 10dabaa..72c5434 100644
--- a/can-halal.c
+++ b/can-halal.c
@@ -230,12 +230,14 @@ HAL_StatusTypeDef ftcan_get_tx_queue_length(uint32_t *length) {
 }
 
 #if FTCAN_NUM_TX_BUFFERS
+static_assert(FDCAN_TX_BUFFER11 == 1 << 11 && FDCAN_TX_BUFFER21 == 1 << 21, "Your HAL version has a different definition for the transmit buffer indices. Please update your HAL version or change the code below.");
+
 HAL_StatusTypeDef ftcan_transmit_buffer(uint16_t id, const uint8_t *data, size_t datalen, uint32_t buffer_index) {
     static FDCAN_TxHeaderTypeDef header;
     if (buffer_index >= FTCAN_NUM_TX_BUFFERS) {
         return HAL_ERROR;
     }
-    return HAL_FDCAN_AddMessageToTxBuffer(hcan, fdcan_initialize_tx_header(&header, id, datalen), data, buffer_index);
+    return HAL_FDCAN_AddMessageToTxBuffer(hcan, fdcan_initialize_tx_header(&header, id, datalen), data, 1 << buffer_index);
 }
 #endif // FTCAN_NUM_TX_BUFFERS
 #endif