diff --git a/libavcodec/internal.h b/libavcodec/internal.h
index 9a444fcae7..e676148d75 100644
--- a/libavcodec/internal.h
+++ b/libavcodec/internal.h
@@ -53,6 +53,6 @@ AVHWAccel *ff_find_hwaccel(enum CodecID codec_id, enum PixelFormat pix_fmt);
  */
 int ff_match_2uint16(const uint16_t (*tab)[2], int size, int a, int b);
 
-unsigned int ff_toupper4(unsigned int x);
+unsigned int avpriv_toupper4(unsigned int x);
 
 #endif /* AVCODEC_INTERNAL_H */
diff --git a/libavcodec/mpegvideo.c b/libavcodec/mpegvideo.c
index 7b0cac19e3..c1cd1f7a1d 100644
--- a/libavcodec/mpegvideo.c
+++ b/libavcodec/mpegvideo.c
@@ -646,9 +646,9 @@ av_cold int MPV_common_init(MpegEncContext *s)
         yc_size = y_size + 2 * c_size;
 
         /* convert fourcc to upper case */
-        s->codec_tag = ff_toupper4(s->avctx->codec_tag);
+        s->codec_tag = avpriv_toupper4(s->avctx->codec_tag);
 
-        s->stream_codec_tag = ff_toupper4(s->avctx->stream_codec_tag);
+        s->stream_codec_tag = avpriv_toupper4(s->avctx->stream_codec_tag);
 
         s->avctx->coded_frame= (AVFrame*)&s->current_picture;
 
diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index ac4de7da4a..c1a5c19e04 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -1269,7 +1269,7 @@ int av_lockmgr_register(int (*cb)(void **mutex, enum AVLockOp op))
     return 0;
 }
 
-unsigned int ff_toupper4(unsigned int x)
+unsigned int avpriv_toupper4(unsigned int x)
 {
     return     toupper( x     &0xFF)
             + (toupper((x>>8 )&0xFF)<<8 )
diff --git a/libavformat/utils.c b/libavformat/utils.c
index 1c1a7482e5..d0a7fb90be 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -2148,7 +2148,7 @@ enum CodecID ff_codec_get_id(const AVCodecTag *tags, unsigned int tag)
             return tags[i].id;
     }
     for(i=0; tags[i].id != CODEC_ID_NONE; i++) {
-        if (ff_toupper4(tag) == ff_toupper4(tags[i].tag))
+        if (avpriv_toupper4(tag) == avpriv_toupper4(tags[i].tag))
             return tags[i].id;
     }
     return CODEC_ID_NONE;
@@ -2807,7 +2807,7 @@ static int validate_codec_tag(AVFormatContext *s, AVStream *st)
     for (n = 0; s->oformat->codec_tag[n]; n++) {
         avctag = s->oformat->codec_tag[n];
         while (avctag->id != CODEC_ID_NONE) {
-            if (ff_toupper4(avctag->tag) == ff_toupper4(st->codec->codec_tag)) {
+            if (avpriv_toupper4(avctag->tag) == avpriv_toupper4(st->codec->codec_tag)) {
                 id = avctag->id;
                 if (id == st->codec->codec_id)
                     return 1;