diff --git a/fio.h b/fio.h
index bcd188b..6ee0d6a 100644
--- a/fio.h
+++ b/fio.h
@@ -393,7 +393,7 @@
 	unsigned int thinktime_blocks;
 	unsigned int fsync_blocks;
 	unsigned int start_delay;
-	unsigned long timeout;
+	unsigned long long timeout;
 	unsigned int overwrite;
 	unsigned int bw_avg_time;
 	unsigned int loops;