diff --git a/libavformat/avio_internal.h b/libavformat/avio_internal.h
index 8b9e048f73..11060e9ff9 100644
--- a/libavformat/avio_internal.h
+++ b/libavformat/avio_internal.h
@@ -100,7 +100,7 @@ void ffio_init_context(FFIOContext *s,
  */
 int ffio_read_indirect(AVIOContext *s, unsigned char *buf, int size, const unsigned char **data);
 
-void ffio_fill(AVIOContext *s, int b, int count);
+void ffio_fill(AVIOContext *s, int b, int64_t count);
 
 static av_always_inline void ffio_wfourcc(AVIOContext *pb, const uint8_t *s)
 {
diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
index 28db2c7dbd..d79e41ca77 100644
--- a/libavformat/aviobuf.c
+++ b/libavformat/aviobuf.c
@@ -201,7 +201,7 @@ void avio_w8(AVIOContext *s, int b)
         flush_buffer(s);
 }
 
-void ffio_fill(AVIOContext *s, int b, int count)
+void ffio_fill(AVIOContext *s, int b, int64_t count)
 {
     while (count > 0) {
         int len = FFMIN(s->buf_end - s->buf_ptr, count);