diff --git a/libavformat/avidec.c b/libavformat/avidec.c
index 6112af4..a05d648 100644
--- a/libavformat/avidec.c
+++ b/libavformat/avidec.c
@@ -546,6 +546,10 @@ static int avi_read_header(AVFormatContext *s, AVFormatPara
             avio_rl32(pb); /* quality */
             ast->sample_size = avio_rl32(pb); /* sample ssize */
             ast->cum_len *= FFMAX(1, ast->sample_size);
+            if (ast->cum_len*ast->scale/ast->rate > 3600) {
+                av_log(0,0,"crazy start time, iam scared, giving up\n");
+                return AVERROR_INVALIDDATA;
+            }
 //            av_log(s, AV_LOG_DEBUG, "%d %d %d %d\n", ast->rate, ast->scale, a

             switch(tag1) {