diff --git a/eeprom.h b/eeprom.h
index 1769903..311eee3 100644
--- a/eeprom.h
+++ b/eeprom.h
@@ -2,7 +2,7 @@
 #define eeprom_h
 
 char eeprom_get_char(unsigned int addr);
-void eeprom_put_char(unsigned int addr, char new_value);
+void eeprom_put_char( unsigned int addr, unsigned char new_value );
 void memcpy_to_eeprom_with_checksum(unsigned int destination, char *source, unsigned int size);
 int memcpy_from_eeprom_with_checksum(char *destination, unsigned int source, unsigned int size);