Fix BUILD
diff --git a/BUILD b/BUILD
index aae7b6f..0a188a8 100644
--- a/BUILD
+++ b/BUILD
@@ -479,6 +479,7 @@
         "src/core/lib/iomgr/endpoint_pair_windows.c",
         "src/core/lib/iomgr/error.c",
         "src/core/lib/iomgr/ev_epoll1_linux.c",
+        "src/core/lib/iomgr/ev_epollsig_linux.c",
         "src/core/lib/iomgr/ev_epollex_linux.c",
         "src/core/lib/iomgr/is_epollexclusive_available.c",
         "src/core/lib/iomgr/ev_epoll_thread_pool_linux.c",