diff --git a/libmpdemux/demuxer.c b/libmpdemux/demuxer.c
index 1d1a781648..6db07b1241 100644
--- a/libmpdemux/demuxer.c
+++ b/libmpdemux/demuxer.c
@@ -1017,7 +1017,7 @@ int demux_info_print(demuxer_t *demuxer)
     return 0;
 }
 
-char* demux_info_get(demuxer_t *demuxer, char *opt) {
+char* demux_info_get(demuxer_t *demuxer, const char *opt) {
   int i;
   char **info = demuxer->info;
 
diff --git a/libmpdemux/demuxer.h b/libmpdemux/demuxer.h
index a922456297..73b6bc5194 100644
--- a/libmpdemux/demuxer.h
+++ b/libmpdemux/demuxer.h
@@ -361,7 +361,7 @@ extern int pts_from_bps;
 extern int extension_parsing;
 
 int demux_info_add(demuxer_t *demuxer, const char *opt, const char *param);
-char* demux_info_get(demuxer_t *demuxer, char *opt);
+char* demux_info_get(demuxer_t *demuxer, const char *opt);
 int demux_info_print(demuxer_t *demuxer);
 int demux_control(demuxer_t *demuxer, int cmd, void *arg);