diff --git a/src/dev/channel.c b/src/dev/channel.c
index afcc92b..acb4fdc 100644
--- a/src/dev/channel.c
+++ b/src/dev/channel.c
@@ -7,11 +7,8 @@
  */
 
 #include "log_level.h"
-#ifdef DEFAULT_LOG_LEVEL
-    //#undef DEFAULT_LOG_LEVEL
-#endif
 #ifndef DEFAULT_LOG_LEVEL
-    #define DEFAULT_LOG_LEVEL LOG_TRACE
+    #define DEFAULT_LOG_LEVEL LOG_ERROR
 #endif
 
 #include <string.h>
diff --git a/src/dev/sdc_f256.c b/src/dev/sdc_f256.c
index 48e2f7c..c6f7546 100644
--- a/src/dev/sdc_f256.c
+++ b/src/dev/sdc_f256.c
@@ -23,6 +23,7 @@
 #include "interrupt.h"
 #include "F256/sdc_spi.h"
 #include "sdc_f256.h"
+#include "utilities.h"
 
 /* MMC/SD command (SPI mode) */
 #define CMD0	(0)			/* GO_IDLE_STATE */
@@ -379,7 +380,7 @@ static short sdc_read(p_dev_block dev, long lba, uint8_t * buffer, short size) {
 	p_sd_card_info card = (p_sd_card_info)dev->data;
 	p_sdc_spi sd = card->reg;
 	uint8_t cmd;
-	short count = size % 512 + 1;
+	short count = ceil_div_short(size, 512);
 
 	if (card->status & SDC_STAT_NOINIT) {
     	return ERR_NOT_READY;
@@ -420,7 +421,7 @@ static short sdc_write(p_dev_block dev, long lba, const uint8_t * buffer, short
 	p_sd_card_info card = (p_sd_card_info)dev->data;
 	p_sdc_spi sd = card->reg;
 	uint8_t cmd;
-	short count = size % 512 + 1;
+	short count = ceil_div_short(size, 512);
 
 	if (card->status & SDC_STAT_NOINIT) {
     	return ERR_NOT_READY;
diff --git a/src/toolbox.c b/src/toolbox.c
index 7ffb4b6..760915e 100644
--- a/src/toolbox.c
+++ b/src/toolbox.c
@@ -3,8 +3,8 @@
  */
 
 #include "log_level.h"
-#define DEFAULT_LOG_LEVEL LOG_INFO
-#define LOG_CHANNEL LOG_CHANNEL_UART0
+#define DEFAULT_LOG_LEVEL LOG_ERROR
+#define LOG_CHANNEL LOG_CHANNEL_CHANNEL_A
 
 #include <ctype.h>
 #include <stdio.h>
diff --git a/src/utilities.c b/src/utilities.c
index 24a1174..f1b7fb7 100644
--- a/src/utilities.c
+++ b/src/utilities.c
@@ -7,6 +7,16 @@
 #include <ctype.h>
 #include "utilities.h"
 
+/**
+ * Return the ceiling of a/b using only short operations
+ * 
+ * @param a the numerator
+ * @param b the denominator
+ * @return the smallest short c such that c >= a / b
+ */
+short ceil_div_short(short a, short b) {
+	return (a + (b - 1)) / b; 
+}
 
 /**
  * Re-entrant version of strtok_r, because VBCC does not provide it
diff --git a/src/utilities.h b/src/utilities.h
index c4f2e06..46a2815 100644
--- a/src/utilities.h
+++ b/src/utilities.h
@@ -13,6 +13,15 @@
 /** Return the maximum value of x or y */
 #define max(x, y)   ((x < y) ? y : x)
 
+/**
+ * Return the ceiling of a/b using only short operations
+ * 
+ * @param a the numerator
+ * @param b the denominator
+ * @return the smallest short c such that c >= a / b
+ */
+extern short ceil_div_short(short a, short b);
+
 /**
  * Re-entrant version of strtok_r, because VBCC does not provide it
  *