diff --git a/Adafruit_SPIDevice.cpp b/Adafruit_SPIDevice.cpp
index d5ecdc9..1b6b3bf 100644
--- a/Adafruit_SPIDevice.cpp
+++ b/Adafruit_SPIDevice.cpp
@@ -113,12 +113,15 @@ void Adafruit_SPIDevice::transfer(uint8_t *buffer, size_t len) {
   if (_spi) {
     // hardware SPI is easy
 
-#ifdef SPARK
+#if defined(SPARK)
     _spi->transfer(buffer, buffer, len, NULL);
+#elif defined(STM32)
+    for (size_t i = 0; i < len; i++) {
+      _spi->transfer(buffer[i]);
+    }
 #else
     _spi->transfer(buffer, len);
 #endif
-
     return;
   }