diff --git a/libavcodec/adx.c b/libavcodec/adx.c
index c841e4eb8c..fb91f652cf 100644
--- a/libavcodec/adx.c
+++ b/libavcodec/adx.c
@@ -267,7 +267,7 @@ static uint32_t read_long(const unsigned char *p)
     return (p[0]<<24)|(p[1]<<16)|(p[2]<<8)|p[3];
 }
 
-int is_adx(const unsigned char *buf,size_t bufsize)
+static int is_adx(const unsigned char *buf,size_t bufsize)
 {
     int    offset;
 
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index d4072d9521..9f1a4ae958 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -2530,9 +2530,6 @@ void av_free_static(void);
 void *av_mallocz_static(unsigned int size);
 void *av_realloc_static(void *ptr, unsigned int size);
 
-/* add by bero : in adx.c */
-int is_adx(const unsigned char *buf,size_t bufsize);
-
 void img_copy(AVPicture *dst, const AVPicture *src,
               int pix_fmt, int width, int height);
 
diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index 24fb082186..4ac44c73ac 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -81,10 +81,6 @@ typedef struct AVFrac {
     int64_t val, num, den;
 } AVFrac;
 
-void av_frac_init(AVFrac *f, int64_t val, int64_t num, int64_t den);
-void av_frac_add(AVFrac *f, int64_t incr);
-void av_frac_set(AVFrac *f, int64_t val);
-
 /*************************************************/
 /* input/output formats */
 
diff --git a/libavformat/utils.c b/libavformat/utils.c
index 5a3af68e74..51489a3a48 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -26,6 +26,10 @@
  * Various utility functions for using ffmpeg library.
  */
 
+static void av_frac_init(AVFrac *f, int64_t val, int64_t num, int64_t den);
+static void av_frac_add(AVFrac *f, int64_t incr);
+static void av_frac_set(AVFrac *f, int64_t val);
+
 /** head of registered input format linked list. */
 AVInputFormat *first_iformat = NULL;
 /** head of registered output format linked list. */
@@ -3147,7 +3151,7 @@ void av_set_pts_info(AVStream *s, int pts_wrap_bits,
  * @param num must be >= 0
  * @param den must be >= 1
  */
-void av_frac_init(AVFrac *f, int64_t val, int64_t num, int64_t den)
+static void av_frac_init(AVFrac *f, int64_t val, int64_t num, int64_t den)
 {
     num += (den >> 1);
     if (num >= den) {
@@ -3162,7 +3166,7 @@ void av_frac_init(AVFrac *f, int64_t val, int64_t num, int64_t den)
 /**
  * Set f to (val + 0.5).
  */
-void av_frac_set(AVFrac *f, int64_t val)
+static void av_frac_set(AVFrac *f, int64_t val)
 {
     f->val = val;
     f->num = f->den >> 1;
@@ -3174,7 +3178,7 @@ void av_frac_set(AVFrac *f, int64_t val)
  * @param f fractional number
  * @param incr increment, can be positive or negative
  */
-void av_frac_add(AVFrac *f, int64_t incr)
+static void av_frac_add(AVFrac *f, int64_t incr)
 {
     int64_t num, den;