diff --git a/ffmpeg.c b/ffmpeg.c
index b836448606..29f61da381 100644
--- a/ffmpeg.c
+++ b/ffmpeg.c
@@ -155,8 +155,9 @@ static struct termios oldtty;
 static int restore_tty;
 #endif
 
+#if HAVE_PTHREADS
 static void free_input_threads(void);
-
+#endif
 
 /* sub2video hack:
    Convert subtitles to video with alpha to insert them in filter graphs.