diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index c6709a267b..d97fc33d44 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -4209,6 +4209,8 @@ static int64_t webm_dash_manifest_compute_bandwidth(AVFormatContext *s, int64_t
             // prebuffered.
             pre_bytes = desc_end.end_offset - desc_end.start_offset;
             pre_ns = desc_end.end_time_ns - desc_end.start_time_ns;
+            if (pre_ns <= 0)
+                return -1;
             pre_sec = pre_ns / nano_seconds_per_second;
             prebuffer_bytes +=
                 pre_bytes * ((temp_prebuffer_ns / nano_seconds_per_second) / pre_sec);