diff options
| -rw-r--r-- | src/whirligig.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/src/whirligig.c b/src/whirligig.c index c277cdea..86687f1f 100644 --- a/src/whirligig.c +++ b/src/whirligig.c @@ -331,8 +331,14 @@ static IntegerMatrix *try_all(struct window *win, int n1, int n2, { int i, j; IntegerMatrix *m; - struct image *i1 = &win->img[n1]; - struct image *i2 = &win->img[n2]; + struct image *i1; + struct image *i2; + + assert(n1 >= 0); + assert(n2 >= 0); + + i1 = &win->img[n1]; + i2 = &win->img[n2]; for ( i=0; i<i1->n_crystals; i++ ) { for ( j=0; j<i2->n_crystals; j++ ) { |