diff --git a/libavformat/os_support.c b/libavformat/os_support.c
index 4cdfcea469..219db98c1c 100644
--- a/libavformat/os_support.c
+++ b/libavformat/os_support.c
@@ -16,6 +16,7 @@
  * License along with this library; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
+#include "config.h"
 #include "avformat.h"
 #ifdef CONFIG_WIN32
 #include <sys/types.h>