diff --git a/core/esp_spi.c b/core/esp_spi.c
index 56ed196..02dae76 100644
--- a/core/esp_spi.c
+++ b/core/esp_spi.c
@@ -194,13 +194,13 @@ void spi_transfer(uint8_t bus, void *data, size_t len)
     spi_endianness_t e = spi_get_endianness(bus);
     spi_set_endianness(bus, SPI_LITTLE_ENDIAN);
 
-    size_t counts = len / _SPI_BUF_SIZE;
-    for (uint8_t i = 0; i < counts; i++)
+    size_t blocks = len / _SPI_BUF_SIZE;
+    for (uint8_t i = 0; i < blocks; i++)
         _spi_buf_transfer(bus, data + i * _SPI_BUF_SIZE, _SPI_BUF_SIZE);
 
     uint8_t tail = len % _SPI_BUF_SIZE;
     if (tail)
-        _spi_buf_transfer(bus, data + counts * _SPI_BUF_SIZE, tail);
+        _spi_buf_transfer(bus, data + blocks * _SPI_BUF_SIZE, tail);
 
     spi_set_endianness(bus, e);
 }
diff --git a/core/include/esp/spi.h b/core/include/esp/spi.h
index 6b2b0e2..55b9d14 100644
--- a/core/include/esp/spi.h
+++ b/core/include/esp/spi.h
@@ -12,9 +12,7 @@
 #include <stdbool.h>
 #include <stdint.h>
 #include "esp/spi_regs.h"
-
-// FIXME Better to define it somewhere else. This is not the CPU frequency!
-#define SYSTEM_BUS_FREQ 80000000UL
+#include "esp/clocks.h"
 
 /**
  * Macro for use with spi_init and spi_set_frequency_div.
@@ -121,7 +119,7 @@ void spi_set_frequency_div(uint8_t bus, uint32_t divider);
  */
 inline uint32_t spi_get_frequency_hz(uint8_t bus)
 {
-    return SYSTEM_BUS_FREQ /
+    return APB_CLK_FREQ /
         (((SPI(bus).CLOCK >> SPI_CLOCK_DIV_PRE_S) & SPI_CLOCK_DIV_PRE_M) + 1) /
         (((SPI(bus).CLOCK >> SPI_CLOCK_COUNT_NUM_S) & SPI_CLOCK_COUNT_NUM_M) + 1);
 }