diff --git a/libavformat/utils.c b/libavformat/utils.c
index 64b9b898e6..c64ff27418 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -609,14 +609,15 @@ int ff_bprint_to_codecpar_extradata(AVCodecParameters *par, struct AVBPrint *buf
 
 int ff_dict_set_timestamp(AVDictionary **dict, const char *key, int64_t timestamp)
 {
-    time_t seconds = timestamp / 1000000;
+    int microsecs = timestamp % 1000000;
+    time_t seconds = timestamp / 1000000 - (microsecs < 0);
     struct tm *ptm, tmbuf;
     ptm = gmtime_r(&seconds, &tmbuf);
     if (ptm) {
         char buf[32];
         if (!strftime(buf, sizeof(buf), "%Y-%m-%dT%H:%M:%S", ptm))
             return AVERROR_EXTERNAL;
-        av_strlcatf(buf, sizeof(buf), ".%06dZ", (int)(timestamp % 1000000));
+        av_strlcatf(buf, sizeof(buf), ".%06dZ", microsecs + (microsecs < 0) * 1000000);
         return av_dict_set(dict, key, buf, 0);
     } else {
         return AVERROR_EXTERNAL;