diff --git a/minichlink/minichlink.c b/minichlink/minichlink.c
index 7b756d2c6b3e00ab571bcb94a1975a6fc1996830..cf3f32542a3f32cbfbc33f11f635f6329b458992 100644
--- a/minichlink/minichlink.c
+++ b/minichlink/minichlink.c
@@ -14,7 +14,9 @@
 #include "../ch32v003fun/ch32v003fun.h"
 
 #if defined(WINDOWS) || defined(WIN32) || defined(_WIN32)
+#ifndef _SYNCHAPI_H_
 void Sleep(uint32_t dwMilliseconds);
+#endif
 #else
 #include <unistd.h>
 #endif