diff --git a/src/include/codec.h b/src/include/codec.h
index e68b012..cfd4226 100644
--- a/src/include/codec.h
+++ b/src/include/codec.h
@@ -1,6 +1,12 @@
 #ifndef _CODEC_H_
 #define _CODEC_H_
 
+#ifdef _WIN32
+#define __dllexport __declspec(dllexport)
+#else
+#define __dllexport
+#endif
+
 // Codec callback function
 typedef void (cb_codec)(void* userdata, unsigned char* p, int len);