The sizeof operator returns 4, for an unsigned.

#include <stdio.h>
main() {
printf( "sizeof(unsigned) = %u\n", sizeof(unsigned) );
}

output:

sizeof(unsigned) = 4

it isn't a bug

in p-mode the defualt integer size is long (4 bytes) instead of 
real modes default short (2) bytes.

sizeof(unsigned short) = 2
sizeof(unsigned long) = 4

//default varible is 4 bytes 
sizeof(unsigned) = sizeof(unsigned long)

It's not protected-mode which does that!  DJGPP makes 32-bit programs.
Therefore, integers are four bytes long.  (Protected-mode on the 286
micro-processor is 16 bits.  So, "int"s are the same as "short int"s, there.)