diff --git a/lib_fiber/c/src/common/timer_cache.c b/lib_fiber/c/src/common/timer_cache.c
index c2df38dce..255323b8d 100644
--- a/lib_fiber/c/src/common/timer_cache.c
+++ b/lib_fiber/c/src/common/timer_cache.c
@@ -106,7 +106,7 @@ int timer_cache_remove(TIMER_CACHE *cache, long long expire, RING *entry)
 	}
 
 	if (entry->parent != &node->ring) {
-		// Maybe the fiber has been append to the other ring.
+		// Maybe the fiber has been appended to the other ring.
 		if (ring_size(&node->ring) == 0) {
 			timer_cache_free_node(cache, node);
 		}
@@ -128,7 +128,7 @@ void timer_cache_free_node(TIMER_CACHE *cache, TIMER_CACHE_NODE *node)
 	// The node will be removed if it hasn't any entry.
 	fiber_avl_remove(&cache->tree, node);
 
-	// The node object can be cached for being reused in future.
+	// The node object can be cached for being reused in the future.
 	if (cache->cache_max > 0 && ring_size(&cache->caches) < cache->cache_max) {
 		ring_append(&cache->caches, &node->ring);
 	} else {
diff --git a/lib_fiber/c/src/event.c b/lib_fiber/c/src/event.c
index 8d81c08f9..9cf0e8882 100644
--- a/lib_fiber/c/src/event.c
+++ b/lib_fiber/c/src/event.c
@@ -128,7 +128,37 @@ long long event_get_stamp(EVENT *ev)
 	return ev->stamp;
 }
 
-#ifdef SYS_WIN
+#if	defined(USE_FSTAT_CHECKFD)
+int event_checkfd(EVENT *ev fiber_unused, FILE_EVENT *fe)
+{
+	struct stat buf;
+
+	if (fstat(fe->fd, &buf) == -1) {
+		msg_error("%s(%d): fstat error=%s, fd=%d",
+			__FUNCTION__, __LINE__, last_serror(), fe->fd);
+		acl_fiber_set_error(errno);
+		fe->type = TYPE_BADFD;
+		return -1;
+	}
+
+	if (S_ISCHR(buf.st_mode) || S_ISFIFO(buf.st_mode)
+		  || S_ISSOCK(buf.st_mode)) {
+		fe->type = TYPE_SPIPE | TYPE_EVENTABLE;
+		acl_fiber_set_error(0);
+		return 1;
+# if	defined(HAS_IO_URING)
+	} else if (EVENT_IS_IO_URING(ev)) {
+		fe->type = TYPE_FILE | TYPE_EVENTABLE;
+		acl_fiber_set_error(0);
+		return 1;
+# endif
+	} else {
+		fe->type = TYPE_FILE;
+		acl_fiber_set_error(0);
+		return 0;
+	}
+}
+#elif	defined(SYS_WIN)
 int event_checkfd(EVENT *ev, FILE_EVENT *fe)
 {
 	if (getsockfamily(fe->fd) >= 0) {
diff --git a/lib_fiber/c/src/fiber_io.c b/lib_fiber/c/src/fiber_io.c
index 0afa9707c..52858f2f9 100644
--- a/lib_fiber/c/src/fiber_io.c
+++ b/lib_fiber/c/src/fiber_io.c
@@ -7,7 +7,6 @@
 #include "common/timer_cache.h"
 #include "event.h"
 #include "hook/hook.h"
-#include "hook/io.h"
 #include "fiber.h"
 
 typedef struct {
@@ -178,7 +177,7 @@ void fiber_timer_add(ACL_FIBER *fiber, size_t milliseconds)
 	long long now = event_get_stamp(ev);
 	TIMER_CACHE_NODE *timer;
 
-	fiber->when = now + milliseconds;
+	fiber->when = now + (ssize_t) milliseconds;
 	ring_detach(&fiber->me);  // Detch the previous binding.
 	timer_cache_add(__thread_fiber->ev_timer, fiber->when, &fiber->me);
 
@@ -224,7 +223,7 @@ static void wakeup_timers(TIMER_CACHE *timers, long long now)
 			// timer's arriving.
 			fb->flag |= FIBER_F_TIMER;
 
-			// The fb->me was be appended in fiber_timer_add, and
+			// The fb->me was appended in fiber_timer_add, and
 			// we detatch fb->me from timer node and append it to
 			// the ready ring in acl_fiber_ready.
 			ring_detach(&fb->me);
@@ -282,9 +281,7 @@ static void fiber_io_loop(ACL_FIBER *self fiber_unused, void *ctx)
 			 */
 			while (acl_fiber_yield() > 0) {}
 
-			if (ev->waiter > 0) {
-				continue;
-			} else if (ring_size(&ev->events) > 0) {
+			if (ev->waiter > 0 || ring_size(&ev->events) > 0) {
 				continue;
 			}
 
@@ -359,7 +356,7 @@ size_t acl_fiber_delay(size_t milliseconds)
 	fiber->flag &= ~FIBER_F_TIMER;
 
 	if (acl_fiber_killed(fiber)) {
-		// If been killed, the fiber must has been detatched from the
+		// If been killed, the fiber must have been detatched from the
 		// timer node in acl_fiber_signal(); We call fiber_timer_del
 		// here in order to try to free the timer node.
 		fiber_timer_del(fiber);
@@ -418,7 +415,7 @@ ACL_FIBER *acl_fiber_create_timer(size_t milliseconds, size_t size,
 	fiber_io_check();
 
 	when = fiber_io_stamp();
-	when += milliseconds;
+	when += (ssize_t) milliseconds;
 
 	fiber       = acl_fiber_create(fiber_timer_callback, tc, size);
 	fiber->when = when;
diff --git a/lib_fiber/c/src/hook/poll.c b/lib_fiber/c/src/hook/poll.c
index 19b45f611..e68b13d35 100644
--- a/lib_fiber/c/src/hook/poll.c
+++ b/lib_fiber/c/src/hook/poll.c
@@ -366,7 +366,7 @@ int WINAPI acl_fiber_poll(struct pollfd *fds, nfds_t nfds, int timeout)
 	pe->fds   = pollfd_alloc(pe, fds, nfds);
 #endif
 
-	pe->nfds  = nfds;
+	pe->nfds  = (int) nfds;
 	pe->fiber = curr;
 	pe->proc  = poll_callback;
 
diff --git a/lib_fiber/c/src/stdafx.h b/lib_fiber/c/src/stdafx.h
index 2cf55b67f..451f25ea2 100644
--- a/lib_fiber/c/src/stdafx.h
+++ b/lib_fiber/c/src/stdafx.h
@@ -14,7 +14,7 @@
 #endif
 
 #ifndef _GNU_SOURCE
-#define _GNU_SOURCE
+# define _GNU_SOURCE
 #endif
 
 #include <stdio.h>
@@ -55,6 +55,7 @@
 
 #define STRDUP strdup
 #define GETPID getpid
+#define USE_FSTAT_CHECKFD
 
 #elif defined(SYS_WIN)