diff --git a/libavformat/os_support.h b/libavformat/os_support.h
index 1088c6c31c1c9609edddfd387cbeb6e88ef2663b..3db20a9aa887de20ee90a77a164783eefd84a9be 100644
--- a/libavformat/os_support.h
+++ b/libavformat/os_support.h
@@ -45,6 +45,12 @@ static inline int is_dos_path(const char *path)
     return 0;
 }
 
+#if defined(__OS2__)
+#define SHUT_RD 0
+#define SHUT_WR 1
+#define SHUT_RDWR 2
+#endif
+
 #if defined(_WIN32)
 #define SHUT_RD SD_RECEIVE
 #define SHUT_WR SD_SEND