diff --git a/libavcodec/dirac_parser.c b/libavcodec/dirac_parser.c
index 7dfa3e80f8..647419a385 100644
--- a/libavcodec/dirac_parser.c
+++ b/libavcodec/dirac_parser.c
@@ -207,7 +207,7 @@ static int dirac_combine_frame(AVCodecParserContext *s, AVCodecContext *avctx,
             int64_t pts = AV_RB32(cur_pu + 13);
             if (s->last_pts == 0 && s->last_dts == 0)
                 s->dts = pts - 1;
-            else
+            else if (s->last_dts != AV_NOPTS_VALUE)
                 s->dts = s->last_dts + 1;
             s->pts = pts;
             if (!avctx->has_b_frames && (cur_pu[4] & 0x03))