C program crashes with use of a random variable

I want to populate a grid with 1s and 0s. My program crashes due to the random variable r. It works perfectly fine with a constant(eg: say r=8). I have used srand(time(NULL));

void initGrid(int grid[GRID_HEIGHT][GRID_WIDTH])
{
    int i,j,r;
    for(i=0;i<GRID_HEIGHT;i++)
    {
        r = rand()%10;
        for(j=0;j<GRID_WIDTH;j++)
        {

            grid[i][j]= (i*j+i+j)%(r)<=2?1:0;
        }
    }
}