diff --git a/selfdrive/boardd/spi.cc b/selfdrive/boardd/spi.cc
index e10fd744d5..924f416ead 100644
--- a/selfdrive/boardd/spi.cc
+++ b/selfdrive/boardd/spi.cc
@@ -163,7 +163,7 @@ int PandaSpiHandle::bulk_read(unsigned char endpoint, unsigned char* data, int l
 }
 
 int PandaSpiHandle::bulk_transfer(uint8_t endpoint, uint8_t *tx_data, uint16_t tx_len, uint8_t *rx_data, uint16_t rx_len, unsigned int timeout) {
-  const int xfer_size = 0x40 * 15;
+  const int xfer_size = 0x40 * 5;
 
   int ret = 0;
   uint16_t length = (tx_data != NULL) ? tx_len : rx_len;