diff --git a/libavformat/internal.h b/libavformat/internal.h
index dc76f2c4a7..fee823d32f 100644
--- a/libavformat/internal.h
+++ b/libavformat/internal.h
@@ -320,11 +320,6 @@ void ff_reduce_index(AVFormatContext *s, int stream_index);
 
 enum AVCodecID ff_guess_image2_codec(const char *filename);
 
-/**
- * Convert a date string in ISO8601 format to Unix timestamp.
- */
-int64_t ff_iso8601_to_unix_time(const char *datestr);
-
 /**
  * Perform a binary search using av_index_search_timestamp() and
  * AVInputFormat.read_timestamp().
diff --git a/libavformat/utils.c b/libavformat/utils.c
index cf4124a270..129a49d699 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -4234,18 +4234,6 @@ int ff_find_stream_index(AVFormatContext *s, int id)
     return -1;
 }
 
-int64_t ff_iso8601_to_unix_time(const char *datestr)
-{
-    struct tm time1 = { 0 }, time2 = { 0 };
-    const char *ret1, *ret2;
-    ret1 = av_small_strptime(datestr, "%Y - %m - %d %T", &time1);
-    ret2 = av_small_strptime(datestr, "%Y - %m - %dT%T", &time2);
-    if (ret2 && !ret1)
-        return av_timegm(&time2);
-    else
-        return av_timegm(&time1);
-}
-
 int avformat_query_codec(const AVOutputFormat *ofmt, enum AVCodecID codec_id,
                          int std_compliance)
 {