diff --git a/fftools/cmdutils.c b/fftools/cmdutils.c
index a9809ca087..fa2797ebba 100644
--- a/fftools/cmdutils.c
+++ b/fftools/cmdutils.c
@@ -943,7 +943,7 @@ int check_stream_specifier(AVFormatContext *s, AVStream *st, const char *spec)
     return ret;
 }
 
-AVDictionary *filter_codec_opts(AVDictionary *opts, enum AVCodecID codec_id,
+AVDictionary *filter_codec_opts(const AVDictionary *opts, enum AVCodecID codec_id,
                                 AVFormatContext *s, AVStream *st, const AVCodec *codec)
 {
     AVDictionary    *ret = NULL;
diff --git a/fftools/cmdutils.h b/fftools/cmdutils.h
index 621c5fbe86..8c1bde2a2f 100644
--- a/fftools/cmdutils.h
+++ b/fftools/cmdutils.h
@@ -335,7 +335,7 @@ int check_stream_specifier(AVFormatContext *s, AVStream *st, const char *spec);
  *              If null, the default one is looked up according to the codec id.
  * @return a pointer to the created dictionary
  */
-AVDictionary *filter_codec_opts(AVDictionary *opts, enum AVCodecID codec_id,
+AVDictionary *filter_codec_opts(const AVDictionary *opts, enum AVCodecID codec_id,
                                 AVFormatContext *s, AVStream *st, const AVCodec *codec);
 
 /**