diff --git a/sample/http-server.c b/sample/http-server.c
index 05dc165e..75caa414 100644
--- a/sample/http-server.c
+++ b/sample/http-server.c
@@ -19,6 +19,9 @@
 #include <windows.h>
 #include <io.h>
 #include <fcntl.h>
+#ifndef S_ISDIR
+#define S_ISDIR(x) (((x) & S_IFMT) == S_IFDIR)
+#endif
 #else
 #include <sys/stat.h>
 #include <sys/socket.h>