Fix potential divide by zero.
diff --git a/main.c b/main.c
index 895bcf3..6736b7a 100644
--- a/main.c
+++ b/main.c
@@ -969,7 +969,7 @@ static void *miner_thread(void *userdata)
/* adjust max_nonce to meet target cycle time */
if (diff.tv_usec > 500000)
diff.tv_sec++;
- if (diff.tv_sec != cycle) {
+ if (diff.tv_sec && diff.tv_sec != cycle) {
max64 = work.blk.nonce +
((uint64_t)hashes_done * cycle) / diff.tv_sec;
} else