diff --git a/libtorrent/src/disk_io_thread.cpp b/libtorrent/src/disk_io_thread.cpp
index 673d807f..59eeac9e 100644
--- a/libtorrent/src/disk_io_thread.cpp
+++ b/libtorrent/src/disk_io_thread.cpp
@@ -1772,7 +1772,7 @@ namespace libtorrent
 #endif
 					TORRENT_ASSERT(j.buffer);
 					session_settings const* s = ((session_settings*)j.buffer);
-					TORRENT_ASSERT(s->cache_size >= 0);
+					TORRENT_ASSERT(s->cache_size >= -1);
 					TORRENT_ASSERT(s->cache_expiry > 0);
 
 #if defined TORRENT_WINDOWS