diff --git a/libavformat/utils.c b/libavformat/utils.c
index 671595b4afefa2afb8fc12b57c9d1d0b248b2b03..b90436a97730987e818593cf0212172c8f04837c 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -627,7 +627,7 @@ static void update_initial_timestamps(AVFormatContext *s, int stream_index,
     AVStream *st= s->streams[stream_index];
     AVPacketList *pktl= s->packet_buffer;
 
-    if(st->first_dts != AV_NOPTS_VALUE || dts == AV_NOPTS_VALUE)
+    if(st->first_dts != AV_NOPTS_VALUE || dts == AV_NOPTS_VALUE || st->cur_dts == AV_NOPTS_VALUE)
         return;
 
     st->first_dts= dts - st->cur_dts;
@@ -746,6 +746,7 @@ static void compute_pkt_fields(AVFormatContext *s, AVStream *st,
             of the frame we are displaying, i.e. the last I- or P-frame */
             if (st->last_IP_duration == 0)
                 st->last_IP_duration = pkt->duration;
+            if(pkt->dts != AV_NOPTS_VALUE)
             st->cur_dts = pkt->dts + st->last_IP_duration;
             st->last_IP_duration  = pkt->duration;
             st->last_IP_pts= pkt->pts;
@@ -768,6 +769,7 @@ static void compute_pkt_fields(AVFormatContext *s, AVStream *st,
             if(pkt->pts == AV_NOPTS_VALUE)
                 pkt->pts = st->cur_dts;
             pkt->dts = pkt->pts;
+            if(pkt->pts != AV_NOPTS_VALUE)
             st->cur_dts = pkt->pts + pkt->duration;
         }
     }
diff --git a/tests/libav.regression.ref b/tests/libav.regression.ref
index 02f6faee1d8ff2581b3ec4e7e5b3f0aeeb27a41f..6c5c23690a0ddabdb616aaf01a5f8b27caee5d8d 100644
--- a/tests/libav.regression.ref
+++ b/tests/libav.regression.ref
@@ -11,7 +11,7 @@ bdb7484c68db722f66ba1630cf79844c *./tests/data/b-libav.mpg
 ./tests/data/b-libav.mpg CRC=0x2b71a386
 447b005e527cf495ec13092e788f028d *./tests/data/b-libav.ts
 471692 ./tests/data/b-libav.ts
-./tests/data/b-libav.ts CRC=0xd14320e2
+./tests/data/b-libav.ts CRC=0xcc4948e1
 d6fdeb9f7083cc827f9510c6c4517dc0 *./tests/data/b-libav.swf
 335771 ./tests/data/b-libav.swf
 ./tests/data/b-libav.swf CRC=0xe14e8847