diff --git a/BitRB.h b/BitRB.h
index b734abc..7a240c3 100644
--- a/BitRB.h
+++ b/BitRB.h
@@ -24,7 +24,6 @@ Boston, MA  02110-1301, USA.
 
 #if defined(STM32F10X_MD)
 #include "stm32f10x.h"
-#include <cstddef>
 #else
 #include <Arduino.h>
 #endif
diff --git a/SerialRB.h b/SerialRB.h
index ae28935..3f6719d 100644
--- a/SerialRB.h
+++ b/SerialRB.h
@@ -23,7 +23,6 @@ Boston, MA  02110-1301, USA.
 
 #if defined(STM32F10X_MD)
 #include "stm32f10x.h"
-#include <cstddef>
 #else
 #include <Arduino.h>
 #endif
diff --git a/Utils.cpp b/Utils.cpp
index 985caf4..be1badf 100644
--- a/Utils.cpp
+++ b/Utils.cpp
@@ -58,7 +58,7 @@ uint8_t countBits64(uint64_t bits)
 
 // Simple functions to convert from int to string
 // Example from: https://stackoverflow.com/questions/8257714/how-to-convert-an-int-to-string-in-c
-static uint8_t *i2str_helper(uint8_t *dest, size_t n, int32_t x) {
+static uint8_t *i2str_helper(uint8_t *dest, uint32_t n, int32_t x) {
   if (n == 0) {
     return NULL;
   }
@@ -70,7 +70,7 @@ static uint8_t *i2str_helper(uint8_t *dest, size_t n, int32_t x) {
   return dest + 1;
 }
 
-uint8_t *i2str(uint8_t *dest, size_t n, int32_t x) {
+uint8_t *i2str(uint8_t *dest, uint32_t n, int32_t x) {
   uint8_t *p = dest;
   if (n == 0) {
     return NULL;
diff --git a/Utils.h b/Utils.h
index 01fd85a..b574872 100644
--- a/Utils.h
+++ b/Utils.h
@@ -21,7 +21,6 @@
 
 #if defined(STM32F10X_MD)
 #include "stm32f10x.h"
-#include <cstddef>
 #else
 #include <Arduino.h>
 #endif
@@ -32,7 +31,7 @@ uint8_t countBits32(uint32_t bits);
 
 uint8_t countBits64(uint64_t bits);
 
-uint8_t *i2str(uint8_t *dest, size_t n, int32_t x);
+uint8_t *i2str(uint8_t *dest, uint32_t n, int32_t x);
 
 #endif