  The arithmetic crosscorrelation of binary $m$-sequences with coprime periods
$2^{n_1}-1$ and $2^{n_2}-1$\ ($\gcd(n_1,n_2)=1$) is determined. The result
shows that the absolute value of arithmetic crosscorrelation of such binary
$m$-sequences is not greater than $2^{\min(n_1,n_2)}-1$.
