Static linking issues

shishire@achilles:~$ cat sieve.c
#include <stdlib.h>
#include <math.h>

char*
eratosthenes(int n, int *c)
{
	char* sieve;
	int i, j, m;

	if(n < 2)
		return NULL;

	*c = n-1;     /* primes count */
	m = (int) sqrt((double) n);

	/* calloc initializes to zero */
	sieve = calloc(n+1,sizeof(char));
	sieve[0] = 1;
	sieve[1] = 1;
	for(i = 2; i <= m; i++)
		if(!sieve[i])
			for (j = i*i; j <= n; j += i)
				if(!sieve[j]){
					sieve[j] = 1;
					--(*c);
				}
  	return sieve;
}

int main(int argc, char *argv)
{
	int *array, n=0xFFFF;
	array =(int *)malloc(sizeof(int));
	eratosthenes(n,array);
	return 0;
}
shishire@achilles:~$ gcc -o sieve -static -static-libgcc -static-libstdc++ -lm sieve.c
/tmp/ccgpiyqD.o: In function `eratosthenes':
sieve.c:(.text+0x35): undefined reference to `sqrt'
collect2: error: ld returned 1 exit status